If you only want a countdown timer...really, spend ten bucks on a big digital kitchen timer. We used to velcro one on the cabin bulkhead next to the instruments, so everyone could see if and watch the countdown. Cheap, durable, easy to change the penlight battery every two years. And when not in use, zipzip the velco and it went below as a clock.
I never invested in a "proper" racing watch but at least in theory, it should count DOWN, reset and restart if there's a postponement, and after the countdown switch to counting elapsed time to keep time for the race. Oddly enough many watches will do that--but only keep elapsed time to one hour.
So I've always said "screw it" and used a stopwatch or kitchen time. The smartphones can do better now, but anything on deck eventually tries to go swimming and that never ends well.
Have you tried asking Ronstaan about a band? I'd be surprised if they didn't replace the band, or just send you a new watch. Always worth asking, and giving them a chance to earn good pr