Nano clone - USB won't work after programming

I seem to have done something to a nano of mine.... I've been uploading sketches normally through the web app via USB, and everything was OK. Tonight I worked out how to use my new USBASP programmer, and fiddled with different bootloaders - Optiboot/MiniCore etc. This seemed to go fine, and I could upload sketches through the ICSP header. Now whatever I do I cannot upload a sketch over USB, through either web interface or Mac app (out of sync). I have no trouble using the normal IDE app and the programmer though.... Does anyone know how to fix this? Cheers

When you upload a sketch through the ICSP header, you erase the bootloader. You need to upload the bootloader again if you want to program through the USB interface.

OK, thanks.... I thought using the ICSP header and a programmer was reburning the bootloader.... I'll experiment again. I suspect th menu item 'Burn the bootloader' has something to do with it!

That worked, once…
Using the ?standard board ‘Arduino Nano’, hooked it up via the ICSP, burnt the bootloader, then it would upload sketches via USB as normal.
I couldn’t get it to burn a bootloader from either MiniCore or Optiboot however.

Then I went to plug the 6 pin plug back onto the header, misaligned for a fraction of a second and ended up with Vcc on MISO, lights came on for a fraction of a second. Now no bootloaders will load full-stop. Sketches will load through ICSP without problems…

I wonder if something was fried?