The bottom screws in the picture are the longer ones

Battery is on left side in my UK model. No need to touch right.

Hello. Just finished this successfully. Thank you Deric, your comments really helped. I sourced a straight swap battery (1000mAh) in UK on Amazon UK if you search the head phone model and battery. Deric’s tip to remove the microphones is key to doing. They slide out easily. Soldering would be too difficult for me on this tiny PCB. Thank you. GG.