A few months ago I connected my pi 2B to a faulty power supply, it received just over 6V onto the GPIO for a few hours.
The pi has since continued to work for me in some areas; the USB and Ethernet work fine as does general use of the pi via remote desktop/ssh.
The HDMI port sometimes causes problems...
Firstly, when the pi is powered from my desktop pc I can connect the pi to my monitor and the display works.
When the pi is powered from ANY other device the monitor powers off (screen goes black, power/standby light goes out)
The monitor normally has a green light for on, orange for standby
This list of other devices includes: power from two different phone chargers, power from a battery powered phone charger, power from a desk power supply set to 5v.
Connecting the pi to the monitor without powering the pi allows the monitor to function as expected (i.e. it sits in standby mode)
As soon as power is applied to the pi the monitor powers off completely. I tried dialling the voltage applied to the pi down and found that there is a point where
2 other pi-s work fine from any of these other power supplies with the monitor.
The monitor works fine with three different graphics card.
Any suggestions on what could have been damaged and why it might not be a problem when powered off my computer?