Ahh, the rear caps are stuck?
First off, don't do anything rash; they're plastic and I can't imagine that they'd really get stuck so bad that a little finesse won't pop them right off.
Make sure the breech "ring" is turned all the way to the right (clockwise), if you're looking at the front of the lens. This is in the "locked" position. Once it's all the way, then jiggle the cap around and see if you can get it to seat. To take the cap off properly you need to turn the collar counter-clockwise, then if the cap is in there properly it should effortlessly come right off.
It's possibel that it's jammed; like the collar has been turned hard right while the cap was not properly nestled into it's grooves, resulting in a jam. If that's the case, turn it counterclockwise while jiggling the cap around.
This might not be the proper "order of operations", but maybe it'll give you some way to think about it.
Best of luck, the 35mm f/2.5 is a lens I like quite a bit.