Your TAG hasnt died, it does need an overhaul!
a good TAG dealer will be able to do it, new battery, glass, bezzle, friction-ring, seals, cleaned etc. I paid £125 to get a F1 done and that included a new strap!
and the same to get a rolex serviced-no battery obviously, but new glass, seals etc. it came back like new, not a scratch to be seen!
Also that panerai will cost you rather more than£500, as it says you have push the boat out!!! nice tho