Ive heard of guys flying without the capacitors, but they are available on ebay and I think amazon pretty cheap. I think they just use those capacitors for power filters. Guys are also hot gluing them and checking them often because they vibrate loose or jar loose during crashes. If your vtx gets warm you have power but you could check for 12vt and a good ground. If you have that and tried every channel with no picture you probably need a vtx.
The vtx on the er250 is kind of cheap. I went through several along with cameras until I switched to other brands. I had a pdb start to fail and began wiring to bypass the thin copper strips in the board, until more things started to fail. If that happens you can get a matek board with a 5 vt ubec and just bypass the board entirely. Its kinda a lot of work because the fcb is specifically designed to pair with the lower pdb, but it can be done. You could avoid some of the work by just getting a open source cc3d with normal esc pins. If tou do that you probably should just get new escs with normal esc connecters, because you simonks will need wire extentions for both power and ground and signal. If you get a new fcb and escs you will have to tune. If you keep the same fcb you might not have to tune, but you still might have to if you add lots of wiring and change things around. Just do what you have to do, and deal with the tuning later if needed.