According to frengel’s instructions on iFixIt, replacing the sub-board shouldn’t be too difficult. (EDIT: it is a screw-and-plug job. Steps 9, 10 and 11 may not be needed when only replacing the I2C/I3C sub-board; i.e. you have to
- remove the battery (steps 1 to 5; unscrew and unplug)
- remove the mid-frame (steps 6 to 8; unscrew und removal of one sticker; pay attention to camera(s); they may stick to the mid-frame)
- replace I3C board (step 12; unscrew, unplug and replace)
- reassemble)
Therefore, I would be happy to eventually receive a replacement board that I can mount myself. This would be the easiest solution for Jolla.