Does not start up normally after accident, please help

Hello,
I finished the build and had only some minor issues, but I accidentally put the corner of main board against the +15/-15V rails of the PSU board

All the LEDs went on for a quick while before I could remove the board from the PSU board.
Now the yocto does not start up normally. The display and all buttons light up, but no text is shown on the display.
I already changed the Atmega for a new one.

Where should I start with troubleshooting? Does anybody know which places to test with oscilloscope and/or voltmeter?

Thank you in advance!

I now have discovered that it makes no difference if the Atmega controller is in the socket or not.
All the LEDs are continuously on when the power is on. However when I quickly turn off and on again, only part of the LEDs will be on.
Maybe this is a clue to one of you guys?

cmroosen wrote:I now have discovered that it makes no difference if the Atmega controller is in the socket or not.
All the LEDs are continuously on when the power is on. However when I quickly turn off and on again, only part of the LEDs will be on.
Maybe this is a clue to one of you guys?

Test Digital Ground and Analog Ground continuity.
The LCD should works with the µC, if it's not the case you have an issue with the power supply.

Thanks! By this you mean I will have to check if digital ground and analog ground are connected to the parts which in the schema are grounded?
I think I will place a new LCD as soon as possible just to be sure. Can I use any 16x2 display with a Sitronix ST7066U controller, or HD44780 controller?

Small question: Should the ground point next to TP1 be connected with the main digital ground? Thanks in advance!