Thanks, it worked.
I never disassembled my Jolla before, so I had a bit trouble in removing the upper part of the frame. Some hints for others:

• At the end I used an old credit card on the right top side to apply more force(opposite to the buttons).
• iFixit has a quite decent teardown with pics: https://www.ifixit.com/Device/Jolla
• And as mentioned in above link as well, you will need torx T5 (I was stuck first with a T6 I falsely borrowed from a friend first But if you do first, and think after,.... )