Continue swinging open the back panel until you can rest it on the left edge the phone, being careful not to put any stress on the attached ribbon cable.
During reassembly, this is a good point to power on your phone and test all functions before re-sealing the back panel. Be sure to power your phone back down completely before you continue working.
Whenever you use the spudger near the battery, be very careful not to puncture the battery.
Using the pointed end of a spudger, pry the battery connector straight up from the motherboard to disconnect the battery.
To re-attach press connectors like this one, carefully align and press down on one side until it clicks into place, then repeat on the other side. Do not press down on the middle. If the connector is misaligned, the pins can bend, causing permanent damage.
I've replaced my Pixel 4 XL front camera as instruction; but unfortunately,my face ID doesn't work after replacement. It kept showing "Enrolment was not completed. Certificate expired."