The area you highlight is unlikely to make much difference. Those are chokes to keep high frequencies (probably the LO or LO/2) coming out of the IF port. That shouldn't stop it working.
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First, bake it for a few hours at about 80 degrees.
I've highlighted the areas that are more likely to have stopped it working. It's hard to see from the photos but there may be connections across the inter-stage coupling lines. Before you start, measure the current drawn by just the LNB and record the noise profile on Crazyscan or IQ Monitor etc. From memory, the current is normally around 120-130mA.
I would get a small, short haired, stiff brush and some IPA (Propan 2 ol). Scrub the whole board paying special attention to the corroded areas. Also clean up the soldered areas. That is best done under a stereo microscope or good magnifier. Take care not to do any more damage when scrubbing. You might need to us a needle to clear areas between tracks but make sure those areas are meant to be clear. Give it another clean after using a needle to remove anything disturbed. Make sure that the oscillator under the board looks clean. Once you've cleaned it, check again to see if there are any breaks in the thin tracks.
Re-check the current and noise profile. Has anything changed? If so, it is worth testing again on the dish.
Good luck.