I presume you mean the screw heads are stripped (washed out) rather than the screw threads. The former is easy to remedy with new screws, the latter might involve body replacement.So I did manage to take the cover off. But while putting in the new cover I stripped a couple of screws!!!
This is what I'd try first. You should be able to carefully remove them with the right pair of pliers.you may be able to firmly grab them with needle nose pliers, duckbills or Visegrips and gingerly unscrew them