I de-soldered the battery and installed a new battery holder for a CR 2032 battery. In this way I can easily change it in the future. I would not recommend this job for someone that has no electronics experience by the way. Taking the synth apart, removing the board and getting everything back together is not a very easy task. The new battery measured 3.2 Volts by the way after I installed it. So maybe the old one wasn't as good anyway anymore. After this measurement I put the synthesizer together and I switched it on. It still seems to work, but it gave the same problem as before, so I did another factory reset. I hope it will stay OK now.
After that I decided to find a new place for the Alesis Andromeda, since its place was takes yesterday by the Moog Memorymoog. I took the Roland V-Synth GT and Yamaha Motif XS6 from their spot and raised the keyboard stand a bit so that another stand could fit under it. And there was the new spot for the Andromeda :) It is a bit lower than the XS6 used to be, but the result is a way nicer height for me to play on it. Another advantage is that I can also see the display better now. And even though this is a an analog synthesizer, but as you can see on the inside there is way more digital electronics in it and no discrete electronics stuff at all, so for me as of today it qualifies as a digital synthesizer ;) OK enough about this. Mission accomplished.