Arduino Nano - verification error when programming bootloader

Hi there,
i try to program my Arduino Nano with Nick Gammons Atmega bootloader programmer. Til now the Nano has been working well but at the moment it stopped accepting new uploads. so i tried to flash a new bootloader via an arduino uno. In the process i get this verification error:

Atmega chip programmer.
Written by Nick Gammon.
Version 1.38
Compiled on Jul 19 2018 at 19:14:24 with Arduino IDE 10803.
Attempting to enter ICSP programming mode …
Entered programming mode OK.
Signature = 0x1E 0x95 0x0F
Processor = ATmega328P
Flash memory size = 32768 bytes.
LFuse = 0xFF
HFuse = 0xDA
EFuse = 0xFD
Lock byte = 0xFF
Clock calibration = 0x91
Type ‘L’ to use Lilypad (8 MHz) loader, or ‘U’ for Uno (16 MHz) loader …
Using Uno Optiboot 16 MHz loader.
Bootloader address = 0x7E00
Bootloader length = 512 bytes.
Type ‘Q’ to quit, ‘V’ to verify, or ‘G’ to program the chip with the bootloader …
Erasing chip …
Writing bootloader …
Committing page starting at 0x7E00
Committing page starting at 0x7E80
Committing page starting at 0x7F00
Committing page starting at 0x7F80
Written.
Verifying …
Verification error at address 7E00. Got: 0xFF Expected: 0x11
Verification error at address 7E01. Got: 0xFF Expected: 0x24
Verification error at address 7E02. Got: 0xFF Expected: 0x84
Verification error at address 7E03. Got: 0xFF Expected: 0xB7
Verification error at address 7E04. Got: 0xFF Expected: 0x14
Verification error at address 7E05. Got: 0xFF Expected: 0xBE
Verification error at address 7E06. Got: 0xFF Expected: 0x81
Verification error at address 7E08. Got: 0xFF Expected: 0xF0
Verification error at address 7E09. Got: 0xFF Expected: 0xD0
Verification error at address 7E0A. Got: 0xFF Expected: 0x85
Verification error at address 7E0B. Got: 0xFF Expected: 0xE0
Verification error at address 7E0C. Got: 0xFF Expected: 0x80
Verification error at address 7E0D. Got: 0xFF Expected: 0x93
Verification error at address 7E0E. Got: 0xFF Expected: 0x81

Is the Nano gone or is there a possibility to restore it?

Greets Oli