According to NASA's blog [0] they believe the problem is between the FDS computer and the TMU (the outbound radio modulator). The other two onboard computer systems, CCS and AACS, they believe are still working. All three systems are dual redundant pairs of computers. So, even if one FDS was damaged, in theory they should be able to switch to the other. The blog post is vague on what exactly they tried - "the team tried to restart the FDS and return it to the state it was in before the issue began, but the spacecraft still isn’t returning useable data" - so I don't think we can rule out there are other things they can still try.

[0] https://blogs.nasa.gov/sunspot/2023/12/12/engineers-working-...