How to restore the correct operation of the NP-FW50 battery from the Sony a6000 camera?

Question

Rechargeable batteries

Good day,
Please help me to solve the problem. I have a camera Sony A6000. I bought batteries for it ( analogues ) - the characteristics are the same. They work.
More precisely, they worked before I bought an external charger -. Needed for an external universal battery to charge from USB.
It turned out that after this charge (connected through a proprietary Sony charger to a socket), the battery gives out about 8.4 V, although it should be 7.2. Now both the native branded and Chinese brothers do not want to be charged through the camera. The light on the camera does not light up, the charge does not occur! I assume that the reason is the increased voltage. although the camera works with these batteries! Now I'm afraid that you can damage the camera with increased voltage ...
Another thought - they were charged so most likely due to the fact that charging was designed for USB 5V. On the charging itself, the output is 4.2 / 8.4V. As I understand it - USB / socket. By the way, I found a photo of a branded charge - it also has 8.4 at the output. It seems to be the same, but the battery should give out 7.2 .. and the multimeter shows 8.4V The
question is - is it possible to restore the battery to charge from the camera and how to do it? I suppose that you need to discharge it to the end and try to charge it from the camera .. right? Most likely it will not work through the camera because it turns off when the charge is low. Lightbulb? What light bulb do you need? Maybe there are other ways?

Answer 1

I bought an analogue of this battery from AcmePower. The same. The camera is not charging.
Today I will check the original battery and charging from another camera ...
UPD: Sony support hinted that the problems could be due to the firmware. A new version has just been released. Problem solved by updating the firmware of the camera! Hurrah!

Answer 2

I suppose that you need to discharge it to the end and try to charge it from the camera .. right?

just use them. As it is a little discharged, it will start charging again.
Why do you think so?
Nominal (it is also the minimum) voltage - 2 x 3.6V = 7.2V
Fully charged battery voltage - 2 x 4.2V = 8.4V
Batteries are in good order and fully charged. that's why they don't charge.
Don't be afraid, the voltage is normal.
You simply did not measure the voltage on the batteries with a tester before, and did not know this.