MGL Avionics User Forum

is there somewhere list of error messages, and what they mean?

While starting an unit that has been long in storage, it says
"Cannot deermine Flash type"

and stops.

This means it is not able to read the flash memory chip on the CPU board - you have two of them. This contains the Enigma application and is also used to create a disk to hold data such as your screen files etc.
The most common issue on these boards is due to them being built with lead free solder. In the early days of this technology forced by legislation it was common for the solder to grow "tin whiskers" over time for reasons not really well understood. Effectively very thin stands of tin would grow at a solder pad and eventually join an adjacent pad creating a short. These are so thin you normally cannot see them with a naked eye but are readily seen under magnification.
Have a close look between every pad on both the flash and the two RAM chips (they share common signals) and use a thin blade such as a scalpel to clean the area between the pins/legs of these chips.

As addition infor, the unit did work for one day, before this error happened.

I did look for whiskers with about 100x magnification. And did found clearly one such. Opened that with scalper.

Also checked the other 200'ish legs. And cleaned suspicious. Blown any chips clear of the board.
But starting unit gives that error message.

Any other ideas to try?

The whisker you found may have lead to damage - that's my best guess. In such a case the only real option would be to scope the address and data lines to see if any of these are not toggling or are in an illegal state (i.e. not zero or 3V but something else).
It's probably not feasible to repair given you are dealing with a BGA package used by the CPU and a 6 layer PCB.