This is a really good topic with two issues. How long can electronics keep working and how long can batteries last ?
I too have a Casio calculator that I bought for college in 1981. Still going strong.
A 1982 Yaesu FT790 transceiver with its original Ni-Cds still holding charge.
A Grundig radio in my workshop has played all day for 40 years. Stirling service !
Stuff can be still be designed for microscopic power consumption. My mobile phone is a Nokia 100.
They claim 'Up to 35 days standby'. Unbelievable but true (with a very local base station).
Unfortunately, our bikes get frozen, baked, and rattled about. Then we sting our batteries with 1C+ discharges.
Clearly they're doomed, but I'd love to hear of more unlikely consumer electronics survivors.
What have you got, fellas ?