Error message: "Fingerprint not available"

Hi. Earlier I posted a question about this and I thought it had to do with battery. Now I think it more likely has to do with my opening the palm rest yesterday. But I did put back the palm rest just as it was originally, including making sure the fingerprint reader sensor was plugged tightly back. Now I opened it again to check this, and made sure the sensor is correctly plugged. But when I turn on the computer it still says fingerprint not available, and had to use password to log in. Could someone help explain this? What should I do?

Thanks again as ever!

 

Don't take this question offensively: How much experience do you have in working on laptop hardware?
I ask because not many people have much experience, and you might think it's plugged in properly, but it may not actually be.
Usually those ribbon cables plug into a locking connector, and in order to re-seat that cable, you must unlock the connector.

 

Hep!, I really don't think I made any mistake putting it back, because I did this several times, all the previous cases the fingerprint system worked afterwards. I searched the web and it seems some people also had fingerprint system not available from time to time for unknown reason. Some seemed to then removed the software then downloaded different versions of the driver etc. I just recalled yesterday after the last time I opened it, I turned on the computer with AC adapter and the fingerprint reader worked (although my finger didn't scan well for many times). So I'm really puzzled. Could it really have to do with battery versus AC? It shouldn't, I would think.

Edit:
It's working now, still using battery but why it failed is still a mystery God knows, it could happen again