First check battery health, it should be below 80% or they will not change it.I'll go to their service center on Monday to replace my oneplus 6 battery and back cover. Hopefully it's not already crowded and battery is still in stock.
I'm in the same boat. Back glass cover and battery, both needs to be changed.Hmmm I need to get the back on my OP6 replaced anyway. Should avail of this offer.
That's the most logical thing to do for OP as the batteries might be closing in on expiry considering the age of the phones. They will have to dispose these old batteries as e-waste which will still cost them, so it is easier to just dispose of it this way while earning something through the labour charges.Damn! I had the battery in my OP3 replaced for Rs. 1400 in October last year only to replace the phone in April this year. The replaced battery was decent initially, but its performance wasn't the same as that of a battery in a new phone and in just a 2 months it was not able to retain charge to the same degree. So, either apps consume a lot of battery now or these batteries are just past their lifetime.