Key fob stop working

[martyk]

Key fob stop working, I put in new battery, and it still doesn't work. My other key fob work just fine. Does any one any idea. Thanks for the help. I have a 2012 Genesis.

Marty

 

[Riickk]

When I bought my '07 ES350 in 2018, guy who owned it said one of the FOBs didn't work right.
Batteries you buy at drugstore, supermarket, big box stores may or may not be fresh / fully charged.
These coin batteries are marked 3v (3 volts) but if you measure voltage with a multimeter, fresh battery will show anywhere from 3.1 to 3.3 volts - once they're at 3.0 volts or less, I toss them out, they're dead AFAIC.
Buy a cheap multimeter at Harbor Freight ((around $7)) and you'll have a useful tool for years.

So for my "new" Lexus, I bought ten (10) *fresh* batteries on eBay, and have never had a problem with either FOB; I change the batteries in both FOBS every 6 months; each battery runs around $0.35, although you can pay as much as $1.50... so call it $4 a year for no aggravation.
Suggest you have current FOB-battery tested, or just slap a new (Tested for voltage!) battery in, and see if it makes a difference.
Good Luck !!