Here is the update:
1- The chip on the pro mini clone is a 328p
2- I enabled the verbose output during upload
3- The ISP sketch said pin 10 was the reset pin to the target microcontroller (helps to read the code comments!). So I moved the reset to pin 10 on the MEGA and got this error:
avrdude: Version 6.3, compiled on Jun 14 2016 at 19:15:19
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2014 Joerg Wunsch
System wide configuration file is "/Users/Mike/Library/Arduino15/packages/arduino/tools/avrdude/6.3.0-arduino2/etc/avrdude.conf"
User configuration file is "/Users/Mike/.avrduderc"
User configuration file does not exist or is not a regular file, skipping
Using Port : /dev/cu.usbmodem411
Using Programmer : stk500v1
Overriding Baud Rate : 19200
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 : STK500
Description : Atmel STK500 Version 1.x firmware
Hardware Version: 2
Firmware Version: 1.18
Topcard : Unknown
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% 0.03s
avrdude: Device signature = 0x1e950f (probably m328p)
avrdude: erasing chip
avrdude: reading input file "0x3F"
avrdude: writing lock (1 bytes):
Writing | ################################################## | 100% 0.01s
avrdude: 1 bytes of lock written
avrdude: verifying lock memory against 0x3F:
avrdude: load data lock data from input file 0x3F:
avrdude: input file 0x3F contains 1 bytes
avrdude: reading on-chip lock data:
Reading | ################################################## | 100% 0.01s
avrdude: verifying ...
avrdude: 1 bytes of lock verified
avrdude: reading input file "0x05"
avrdude: writing efuse (1 bytes):
Error while burning bootloader.
Writing | ***failed;
################################################## | 100% 0.07s
avrdude: 1 bytes of efuse written
avrdude: verifying efuse memory against 0x05:
avrdude: load data efuse data from input file 0x05:
avrdude: input file 0x05 contains 1 bytes
avrdude: reading on-chip efuse data:
Reading | ################################################## | 100% 0.01s
avrdude: verifying ...
avrdude: verification error, first mismatch at byte 0x0000
0xfd != 0x05
avrdude: verification error; content mismatch
avrdude done. Thank you.
3a - I left the reset on pin 10 and used the Uno as the board and re-tried to burn the bootloader. I got what I think is the same error.
4- I went back to pin 53 on the MEGA and re-tried to burn the bootloader with the Uno board selected (I had already tried this before with the pro mini board type selected) and got this error:
avrdude: Version 6.3, compiled on Jun 14 2016 at 19:15:19
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2014 Joerg Wunsch
System wide configuration file is "/Users/Mike/Library/Arduino15/packages/arduino/tools/avrdude/6.3.0-arduino2/etc/avrdude.conf"
User configuration file is "/Users/Mike/.avrduderc"
User configuration file does not exist or is not a regular file, skipping
Using Port : /dev/cu.usbmodem411
Using Programmer : stk500v1
Overriding Baud Rate : 19200
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 : STK500
Description : Atmel STK500 Version 1.x firmware
Hardware Version: 2
Firmware Version: 1.18
Topcard : Unknown
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% 0.03s
avrdude: Device signature = 0x000000 (retrying)
Reading | ################################################## | 100% 0.02s
avrdude: Device signature = 0x000000 (retrying)
Error while burning bootloader.
Reading | ################################################## | 100% 0.02s
avrdude: Device signature = 0x000000
avrdude: Yikes! Invalid device signature.
Double check connections and try again, or use -F to override
this check.
avrdude done. Thank you.
5- Reading the sketch again it said to uncomment a #define line to use pins 11, 12, and 13 for MOST, MISO, and SCK on the MEGA. I connected to pins 11, 12, and 13 before uncommenting line and uploading the revised sketch but something interesting happened - when I connected pin 13 the AREF LED on the MEGA turned off. If I remove pin 13 the LED comes right back on. What would cause that?? If leave the code commented I get the same "device signature" error and if I uncomment the line and re-upload to the MEGA I get the "verification error".
6- I tried the SPI pins on the MEGA for the heck of it - get the same "device signature" error (both pro mini and Uno boards were tried).
7- I'm about to give up
Any help in reviewing the errors would be much appreciated. I'm feeling like this is a wiring/code mismatch.