Water damage to Nokia 2730c?

Familiar story. Putting my shorts in bowl to soak. Realised at last second that phone was in pocket. Pulled them out immediately. Phone dead. Dried phone exterior, took back off. Only a few droplets inside on top of and under the battery. Dried inside and stuck phone near radiator to dry off. Switched on and relieved when it sparked up. Reset time and date, sent a text to my mate, all ok.
About 30 minutes later, display suddenly lights up and asks me to enter PIN code. Put code in and it goes dead - and has been ever since.
Seems starnge that it recovered and then failed again. Any ideas anyone?