I have another Nano board with 328P and tried the USBTiniISP on it and success!!! Short lived though
, every upload after the initial one failed, however the LED is blinking so some code is getting through, I also tried to upload the arduino bootloader which also failed with same mismatch error.
For a while I was able to unplug the usb cable at the PC socket and reinsert with the first upload being a success then failure afterwards. I changed Nano boards to try to replicate the issue on the other board and could not reproduce on this board and then neither on the first board afterwards.
Seems like a noise issue to me
Changed USB cable and still the same behavior. Bruise on front of head from banging against wall.