Fob key issue. Locks but does not unlock. Blinking light.

I've been searching through the forums but have not been able to find a suitable solution for my issue. I'll try to explain as detailed as possible.

I've just bought a second (or third, fourth) hand 2008 Prius. I've had a 2005 model before so I know my way around the car.
This car came with 2 fobs. One is working perfectly, the other had no battery when I got it. It may have gone unused for quite a while.

I put a fresh battery (was still sealed and bought recently) in the remote control. For some reason, it doesn't work as it should:

• The RFID chip works fine, I can start the car when the fob is inserted.
• I can lock the car remotely with the lock button
• I cannot unlock the car with the faulty fob.
• When I press the lock button on the remote, the red light on the remote blinks for about 30 seconds.

I've tried to rule out that the button was stuck:

• When I press lock on the faulty remote, the doors lock and the light keeps blinking
• I can press unlock on the working remote and the car unlocks
• While the light on the faulty remote is still blinking, it doesn't re-lock the car. So I'm assuming the button isn't stuck (otherwise it would probably re-send the signal to lock the car).
• The buttons both feel as clicky as the working fob, which adds to my confidence that there's no dirt inside the button.

I tried re-pairing the faulty fob with some success.
Using procedure C explained here: https://priuschat.com/threads/how-to-program-a-new-key-fob-for-full-sks-functionality.133877/#post-1907271 I was able to get the key working for both locking and unlocking yesterday. However, after a couple of minutes after locking the car, the key fob would start blinking. I could then only unlock the car by first pressing lock, then unlock.

Today, the key is back to only locking and blinking for 30 seconds. I'm assuming the blinking is trying to tell me something but I can't find anything about it anywhere.

Really hope someone can help me with this. If not I'm ok with finding a new fob and programming it myself, I'm just not quite sure where I would go for that.

Thanks for reading the lengthy message and hopefully someone knows how to solve this.

 

That may well be the case.. seems like possibly both buttons are faulty in some way then, where the lock button keeps sending for about 30 minutes and the unlock button does nothing...

I guess there's no other fix than getting a new fob (or some quite skilled soldering action)?

Still love to hear from others if anyone has a suggestion.