Before you do anything make sure you have a good strong battery. Short of a professional repair (CLA) you 1st might want to inspect the shutter release magnet. It is easily accessed by removing the bottom plate. It has a protective plastic cover. The magnet and contacts can get corroded or contaminated and the end result is shutter problems. You can trip the shutter with the bottom plate off and watch the lever and magnet action. When it fails to release you can give a nudge to the appropriate lever to see if the magnet will release. Problem of course may be elsewhere. If you elect to tinker under the top plate (research first before you consider it) be very careful not to disturb the meter wire or tweak around of the various soldered wires. Printed circuits etc. under the top plate can appear complex unless you really know what you are doing. Internet search will provide sites with repair tips if not a free download repair guide. Try a search of this site's archives. There are individuals on this forum who are much more experienced than I am at camera repair so let's hope they will add some enlightened comments. Camera repair is not for everyone but some repairs are not too difficult for the 'prepared' novice.