It does look like the bottom right cap has expanded on the top. This partion of the amp is the power supply. It is possible that the cap has deteriated over time and just went bad. In my experience with amp repairs, something always causes the cap to overload and short.
You can take my advise with a grain of salt here.
If it was my amp, I would remove that 1 cap, and bench the amp without a load or input, just to see if it will sustain operation. Going any further than that would require measuring components to fine the part that has caused the failure.
90% of the time, it is always MOSFETS or FETS in the power supply, but without measuring, it is hard to say.
Good luck.