I have an UNO which has developed a fault somewhere between the 16u2 and the 328p.
D13 is lit all the time and I get out of sync error messages when trying to upload.
I have reprogrammed the 16u2 with flip and the latest hex in an effort to fix it, to no avail, same error.
I have swapped the dip 328p from a working, boot-loading UNO installed, with the same error "out of sync" during program upload.
Any pointers for me? Thanks.
Edit: Uno R3.