Vendor Name: Fairphone
Device name: Fairphone (Gen. 6)
Device CodeName: FP6
Version of /e/OS or Stock which existed previously: 3.0.4-a15-official
Not rooted
Received an OTA update for 3.1.2-a15-20250828521531-official-FP6, device rebooted after installation.
Since then the Slider button has no functionality and both IMEI codes are not read correctly.
IMEI1 (before update): 3590**********
IMEI2 (before update): 3590**********
IMEI1 (after update): 004400152020000
IMEI2 (after update): 004400152020000
Needless to say, after this the network provider rejects any registration of this device, leaving me without phone functionality.
When checking the bootloader via a power on + Volume down, I can see that the IMEI is still shown correctly.
On the good news side of things, Revolut works again. But I cannot log in cause I cannot get the SMS anymore. 
Any input for the IMEI problem is appreciated! 