probably need to get a new front camera flex assembly
https://www.mobilesentrix.com/front-camera-and-proximity-sensor-flex-for-iphone-8-premium
a rear camera
https://www.mobilesentrix.com/back-camera-for-iphone-se-2020-premium
and a power and volume flex cable (this has the flash unit)
https://www.mobilesentrix.com/power-and-volume-button-flex-cable-for-iphone-8
i would have given links for the ifixit store, but they don't list these parts for the SE2020
you could use the front camera flex and volume/power flex for the iphone 8 as well, but it doesn't look like the rear camera has that cross-compatibility.
this all said, there could be damage to the system board in which case replacing those parts may not solve your problem.