Cannot upload anymore to Arduino Nano clone after sprintf?

I am using an Arduino Nano clone to program and use a small I2C, SH1106 OLED. While trying to create a function to give me the length of a char*(as all the solutions I found were for strings, and it would complain if they were replaced by char*), I wanted to convert the integer I got back to char*(due to how the library I am using works) and as such, I used sprintf. Everything was working just fine until i added sprintf, now It looks like my board is bricked, as I cannot upload anything anymore to it.

Code I'm trying to upload:

#include <OneBitDisplay.h>
#ifdef USE_BACKBUFFER
static uint8_t ucBackBuffer[1024];
#else
static uint8_t *ucBackBuffer = NULL;
#endif

#define SDA_PIN 32
#define SCL_PIN 26
#define RESET_PIN -1
#define OLED_ADDR -1
#define FLIP180 0
#define INVERT 0
#define USE_HW_I2C 1

#define MY_OLED OLED_128x64
#define OLED_WIDTH 128
#define OLED_HEIGHT 64

OBDISP obd;

void setup() {
int rc;
rc = obdI2CInit(&obd, MY_OLED, OLED_ADDR, FLIP180, INVERT, USE_HW_I2C, SDA_PIN, SCL_PIN, RESET_PIN, 800000L); // use standard I2C bus at 400Khz
}

void loop() {
  char* msg = "This is a test to see if i can manage to scroll text vertically on this oled screen right here. I will write some more words here so that the text will go off screen, as the small font is really smaller than I originally expected.";
  
  scroll_func(msg);
  
  delay(1000);

}

void scroll_func(char* msg){
  obdSetTextWrap(&obd, 1);
  int start=3;
  for(int i=0; i<1380; i+=126){
    if(start>=0){i=0;}
    obdFill(&obd, 0x0, 1);
    obdWriteString(&obd, i,0,start,(char *)msg, FONT_SMALL, 0, 1);
    if(start>=0){start--;}
    delay(1000);
  }
}

Function which broke everything(which was part of the above code block before):

char* len(char* msg){
  int c=0;
  char* length;
  while(msg[c] != '.'){
    c++;
  }
  sprintf(length, "%d", c);
  return length;
}

Error code received:

Arduino: 1.8.12 (Windows 10), Board: "Arduino Nano, ATmega328P (Old Bootloader)"

C:\Users\DRAGOS~1\AppData\Local\Temp\arduino_modified_sketch_983438\scroll_func.ino: In function 'void loop()':

C:\Users\DRAGOS~1\AppData\Local\Temp\arduino_modified_sketch_983438\scroll_func.ino:28:15: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]

   char* msg = "This is a test to see if i can manage to scroll text vertically on this oled screen right here. I will write some more words here so that the text will go off screen, as the small font is really smaller than I originally expected.";

               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sketch uses 7894 bytes (25%) of program storage space. Maximum is 30720 bytes.
Global variables use 826 bytes (40%) of dynamic memory, leaving 1222 bytes for local variables. Maximum is 2048 bytes.
C:\Users\Dragos SPiridon\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17/bin/avrdude -CC:\Users\Dragos SPiridon\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17/etc/avrdude.conf -v -patmega328p -carduino -PCOM6 -b57600 -D -Uflash:w:C:\Users\DRAGOS~1\AppData\Local\Temp\arduino_build_269143/scroll_func.ino.hex:i 

avrdude: Version 6.3-20190619
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2014 Joerg Wunsch

         System wide configuration file is "C:\Users\Dragos SPiridon\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17/etc/avrdude.conf"

         Using Port                    : COM6
         Using Programmer              : arduino
         Overriding Baud Rate          : 57600
         AVR Part                      : ATmega328P
         Chip Erase delay              : 9000 us
         PAGEL                         : PD7
         BS2                           : PC2
         RESET disposition             : dedicated
         RETRY pulse                   : SCK
         serial program mode           : yes
         parallel program mode         : yes
         Timeout                       : 200
         StabDelay                     : 100
         CmdexeDelay                   : 25
         SyncLoops                     : 32
         ByteDelay                     : 0
         PollIndex                     : 3
         PollValue                     : 0x53
         Memory Detail                 :

                                  Block Poll               Page                       Polled
           Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
           ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
           eeprom        65    20     4    0 no       1024    4      0  3600  3600 0xff 0xff
           flash         65     6   128    0 yes     32768  128    256  4500  4500 0xff 0xff
           lfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           hfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           efuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           lock           0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           calibration    0     0     0    0 no          1    0      0     0     0 0x00 0x00
           signature      0     0     0    0 no          3    0      0     0     0 0x00 0x00

         Programmer Type : Arduino
         Description     : Arduino
         Hardware Version: 2
         Firmware Version: 1.16
         Vtarget         : 0.0 V
         Varef           : 0.0 V
         Oscillator      : Off
         SCK period      : 0.1 us

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x1e950f (probably m328p)
avrdude: reading input file "C:\Users\DRAGOS~1\AppData\Local\Temp\arduino_build_269143/scroll_func.ino.hex"
avrdude: writing flash (7894 bytes):

Writing | avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
Problem uploading to board.  See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

From what I can deduce, the board cannot be written to anymore.

And yes, I have tried all of the first options such as switching COM ports from USB3 to 2, it is running the old Bootloader.

When things go wrong , go back to basics - load the blink program in examples to identify where your problem lies .
Look under tools/ports and select the correct port that is highlighted , make sure you are using a usb lead that has worked before .
Try pressing reset the instance your blink code has completed compiling .

Strings can give problems , it’s extremely unlikely you have “bricked it “ , at worst you might have over written the bootloader , which can be reloaded .

Others will be along with further ideas