Arduino NANO (CH340) error while flashing bootloader Ok. So I'm close to tearing me hair out on this one.

I have a batch of cheap Arduino Nano clones, that just straight up won't work. (I HAVE gotten one of them to work, but I suspect that was by pure coincidence)

Anyway, I feel like I've tried everything to make them work.
I am consistently getting 


  Device signature = 0xffffff


errors from avrdude, which I believe is a hardware problem. Up til now I have tried:


Installed CH340 drivers, no difference
Tried to burn bootloader using Uno as an ISP (with 10uF cap between reset and ground!)
Tried the "(Old Bootloader)" option in the IDE


All I have left is to desolder the entire board and troubleshoot each single component, but... no, I want to keep my sanity intact, thaaank you!

Any ideas on how I should move forward here?
Hit reset randomly in the first few seconds of uploading/burning.