Ours does similar - if I haven't used it for a bit, the first time I push a button it blacks out and powers back up. No click or anything though, just silently fades out.have a honeywell and for ours it's usually the battery level and even it making poor contact in the battery compartment , when the it comes on it draws more current,
it makes a click (although there can't be a hardware relay !?) and I think the battery can't meet that demand so supply to it get's glitched through voltage regulator
Mines a wireless controller!didn't know there was a battery, this in the timer?
not swapped one in 20 years