Question about Sony Mdr-Rf895rk

Once had a problem with the predecessor. Called Sony and asked for a replacement part. Not available, we don't make them, we don't have them. So I had to buy a new one. It's annoying to have to throw away the one that still "works" just because the manufacturers want and need to make a profit. Mine's rattling on the bracket and it's only a matter of time before you have to throw everything away just because a spare part won't be delivered. It will soon be BF and there will certainly be a campaign for the Sony. Protecting the environment, CO2 looks different😏

The red LED is the charging indicator. If the headphone battery is charging even though the LED is not lit, I don't see a problem as long as the sound is being transmitted.

If the battery is still charging, then the LED is probably faulty. If it is transmitting then it lights up green, but even then, if it is still connected and has sound, then it is probably the LED.
I've had mine for about 5 years now and have already had to change the battery twice. In both cases, the battery was charged when I put the headphones on the charging station (red LED), but the battery was then empty when I wanted to use the headphones again the next day. The battery is available from Digitec.

Unfortunately I can't answer that. I gave the headphones away...