I've found that the 2025 batteries in these fobs are very weak, even the same brand from a reputable source didn't work. Instead I crushed a 2032 inside, the battery doesn't sit in the clip properly but you can just get the cover to close.
The extra thickness gives nearly double the mAh, so lasts much longer in storage and use.
That's the thread I posted, an "old Skoda trick". What I left out first time round in writing it, is the bradel you use to pop the battery out with, you insert as you close the case to keep the battery snuggly down as the case clip holds the battery in rather than the battery clip in the case. Think my new Duracells were more slippery than the Panasonics that kept bouncing out and prevented the case from closing or using the technique once leads to that effect
. Still side inserting a bradel to keep it in position as you finally close the case is the secret.
Became evident that measuring the voltage with a meter isn't everything since duff batteries pass that test but still are not capable of powering the remote as you say. You got to have the voltage high as the thread and see a bright glow on the remote LED with a new battery, you can get the high voltage and it still doesn't work, check the LED brightness on the remote and it's dim. That's what happened on my remaining just going out of date unused Panasonic battery. You know when your co-driver is careful with money and you want to do a complete change rather than penny pinch ?. Creates more work.
The old
Watts = Volts x Amps
The volts can be correct / pass the test when measured on a new battery but if the battery can't deliver the amps it's not going to work.