Honestly, at this point, given the aging hardware it might be better to replace it with a current device than going this path, as time invested will exponentially rise with lack of prior experience/knowledge unfortunately.
If you don't know what ffp is you most likely didn't install it 10+ years ago and can skip this part, you need to find the alt-f firmware matching your model, flash it through the web interface. Then search through the wiki and this google group for additional steps, the pinned ones and whatever else people over the years already solved.