Weird lockup on HR-16 during LTC1799 installation

[johnny_dub]

Hi Guys,
I installed the circuitbenders.co.uk LTC1799 chip in my HR-16 and everything worked perfect for about 5 minutes. While i was testing the master pitch functionality I realized
I suddently can't stop the sequencer for some reason, so I switched the machine off and since then the machine doesn't boot anymore. The screen is stuck only showing a  _  ??!
https://ibb.co/YjRnR8S
I looked for shorts in my soldering but couldn't find anything...then i removed the pitch mod completely to see if that helps no luck at all.
Did anyone ever run in this problem with the HR-16 not booting but only showing a " _ " on the LCD. Did maybe the SRAM fail or some other part?
I would be very happy if someone could point me in the right direction what could be wrong with my device as i would love continue working on it.
Thanks a lot for your help.

[johnny_dub]

I got it back to life with the self test from the service manual.

[Circuitbenders]

I'm not sure why that would help.
Are you sure you weren't trying to run the clock speed too fast?

[johnny_dub]

Yes...pretty sure. And i have a switch to the standard clock also....the problem remained. The self test erases the memory...don't know why but it helped..had no problems since then. thanks for the answer.