1) Model number is unknown.
2) You have outdoor programmable Intermatic timer, and replaced battery.
3) Open following link to help identify timer and download possible manual:http://waterheatertimer.org/Intermatic-timers-and-manuals.html#hb88
4) If timer does not show on link above, add a comment with clear description of timer and buttons for possible identification and manual.
5) Most battery operated timers require 'reset' after battery change.
Manuals usually say, the battery is replaced and programs remain intact, and then current time has to be set again.
In typical situation however, most timers lose functionality with battery change. That's why timer is reset, and then reprogrammed.
6) If functionality is not restored after battery change and reset, then timer has gone bad.
7) Newer Intermatic timers have 'lifetime' warranty against workmanship defect.
Older timers have 1 year warranty.
8) Electronic timers, low voltage power packs, plus electronic water
heaters, and electronic water softeners and treadmills etc are each
susceptible to power surge from nearby lightning and also from simple
Not always necessary, but safest to unplug outdoor timer during storm event and with circuit breaker trip, or power outage. Plug back in after power is restored or storm is over. This is true also if timer is on GFCI, and breaker trips. Unplug timer and then reset GFCI.
Add a whole house surge protector to main breaker panel. This gives 1-time protection from surge event.
9) Take a moment and rate answer:
And take advantage of fixya expert assistance live.
For a price, expert works with you while you work on timer or any do-it-yourself project.
Fixya is always less expensive than a service call.