Cheap MEGA clone - serial not working

Using Arduino IDE 1.x
1

I have purchased 3 MEGA clones.
They use CH340G for USB2serial.
I am using standard ubuntu with mainline kernel (4.15.5).
2 of the MEGAs work OK, the 3rd one does not - it registers on the system, but refuses to listen to any control commands.
I can connect using another USB2Serial chip to it, program it using the serial chip and USBasp no problem, I can see it's working in serial console of the external chip, but that's it - the onboard one is not working correctly.

Does anybody have any experience with the faulty CH340G chip? There is some X1 header next to it - can I somehow re-flash the chip or something to make it work?

Thanks for any suggestions.

2

Could it be a soldering problem?
Look around the CH340G chip.

3

Tried today to manually re-flow it, unfortunately did not helped :frowning:
The problem is the chip was working for ~2 hours and then died.

4

You might still be able to program it via the ICSP header