ELEGOO Mars failed prints every time
let's go step by step - and rule out the unlikely sources. Since you get at least some results, UV source and screen seem unlikely. Then you might want to make sure that the resin is ok. Let's try to put a droplet onto a sheet of paper/foil, which you tape down outside in the sun or under a UV light source - if it cures, the resin is ok.

The first real step is to check your bed leveling. Go exactly by the handbook - you might be a tad far from the bed, which leads to sticking to the film. 

Then make sure your film is intact. You might need to swap resin vats to do that. in case the film is damaged, you have to swap it.