Timer on turkey won't pop after 4 hours?

The turkey weighs 12-13 lbs. Bought it Friday & put it in a sink full of warm water (wrapper on) for about 4 hours & then put it in the fridge for about 36 hours. We took it out of the fridge this morning and the only part still frozen was the neck/giblets which we threw away anyway. I added about a cup and a half of boiling water to the roasting pan to help it stay moist and cook faster. There is no stuffing inside-- just some onion, celery, and rosemary for flavor. Made an herb er rub & put it under and on top of the skin. We've roasted it at 325 for 2.5 hours & then cranked the heat up to 400. We've kept it basted & even took off the foil. Now it's browned, but the timer hasn't popped up. It's been a little over 4 hours. The drumstick meat is beginning to separate from the bones. :( This is the first turkey I've ever cooked and I followed all the directions. I don't want it to burn if I leave it in the oven, but I don't want food poisoning either. Please share some wisdom/advice! Thanks!