I've just put new pads on shimano deore disc brakes for the first time. I pushed the pistons right in until flush, popped in the new pads easily, but when I pull the lever the pads stay against the disc. It's a slight but continuous rub at the front, but the rear barely moves. I'd recently flushed with worn-out pads, so I thought possibly there was too much oil. I pushed the pistons back in allowing excess to leave, but same problem.
I recently did a long drive with the bike on the back exposed to rain and salt which I don't think helped. Any suggestions?