I have a clone Mega 2560 equipped with a 16U2 that repeatedly loops the installer and seems to never successfully program.
Installation sketch properly selected Mega 16U2 hex
16U2 does not have DFU-enabled bootloader, only USB-CDC
Wiring has been verified from ICSP to ICSP header, ohming at <1ohm
Same for 16U2 Reset to D10
RESET-EN cut after Installer sketch programmed, in lieu of capacitor
"L" LED blinks slowly while TX blinks at same rate (from countdown), then Arduino disconnects from PC for ~10 seconds. L begins blinking slowly once more while TX light blinks quickly, then board reappears
If installation is monitored through USB CDC, the last line printed is "Attempting to enter programming mode ..." before the board disconnects
Board VID/Revision don't change, even upon disconnection or rebooting Windows
Shorting 16U2 Reset twice simply restarts Installer sketch, indicating HL2 was not installed (correct?)
I have a clone Mega 2560 equipped with a 16U2 that repeatedly loops the installer and seems to never successfully program.
I would appreciate any insight you can offer.