Wanted to share a recent experience with my DigiTech 2120 in case someone stumbles upon this and needs a variable to try. March 2016 I put a new battery in and update 2.3 firmware. Earlier this month (March 2017) the battery goes dead (heavy use) so I replace it. Last week I go to turn it on and I get the dreaded saving to program 3 crash. So I reset it and start building again. Turn power off and on again, crash. Kept repeating.
This weekend I decided to take this thing apart and see what is wrong with it. Come to find out, the battery was loose. The metal tab on the bottom became recessed in the battery compartment and wasn’t pushing up to be able to make the top metal tab complete the connection on the top of the battery.
Makes sense that close to 20 years later the metal tab would finally bend down.