Power supply blinking green light

Troubleshooting
1

1.2 RAMPS/Arduino/RPi

This is a weird one for me - when the RPi is connected USB to Arduino USB, the power supply blinks a green light. If I disconnect the USB (unplug the USB cable), the RPi boots fine and is connected to the cloud.

In the course of troubleshooting, I plugged the USB cable back into the Arduino with power on, and the cable heated up enough to melt the outer shield.

Seems like I have power coming across the USB cable. Any thoughts/ideas on how to verify the Arduino/RAMPS is ok? Or, where the current is coming from?

Thx!

2

Ok - ordered a new Arduino Mega and RAMPS board - entirely different Blinky lights than before - seems as though the USB serial port on the Chinese mfg Arduino was blown. Italian version speaks via the com without a problem. Too bad I took this week off to get everything running and failed - sigh. Will hit this project again in a couple of weeks…