A couple of things to check:
#1: The battery of course
#2:Make sure your drop forward screws are not to long and pushing the battery up to crimp the wires. Just pull off the right grip panel with your dropforward on to check.
#3:Take the one screw holding the board in out and make sure no wires are crimped underneath.
#4: Check to make sure your trigger is properly adjusted so it's triggering the selenoid every time you pull the trigger.
#5: Make sure no grease or anything is in your on off switch. I got a nasty gun hit in the switch recentely and had to clean it with electrical cleaner to get it to work properly.
I've had all these item's cause me problems similar to what your describing. Hope this helps,let us know.
P.S. You can dry fire the Timmy just put it in test mode. Works great and yes there is a manual button for the selenoid at the back barely visible beneath the board.