Hi
This cetainly sounds like a memory battery problem, But if you have changed it......
I would suggest, leave the unit plugged in and on for at least 24Hrs. To ensure the battery has full charge.
Then use super user to do a "clear all" followed by a "reset".
This should give you a factory configured desk.
Then put in one simple chase ie chase channels 1 to 12 in 12 steps.
Then run this overnight. Check in the mornig that the chase is still running and is not corrupt.
Then turn the desk off and on a few times, check the chase has not been corrupted.
the desk should now be a "good" desk.
As a general rule it is a good ideas to do a clear all reset betwen hires. As you know what state the desk goes out in then.
Rather than finding the last users put in a strange patch and strobe channels etc.
Hope this helps .... let us know