The board itself holds all the data well a specific chip on there holds it… it's not so simple to just get just the data element over to another phone, it's more practical to fix the board… In order to transfer the data would require a lot of skill havent really worked too much on the xr but I'm assuming it's similar to other iphones, u would need to transfer the eeprom, nand, baseband and cpu to another board and possibly others like wifi if u cant reprogramme the nand. That for data recovery isn't very practical ur better off saying what's wrong with the phone exactly for better advice
Step 19 is sticking the home button down u would just use the widest u can and trim off the excess or use more thinner ones next to each other, which ever u have or whichever is easiest for u, ur just trying to stick the bracket down...
The connector on the 6s isn't too bad its mainly the plus that is temperamental because the connector is physically longer... The problem u describe sounds more like a faulty screen. Disconnect and check the connectors though make sure it's not bent and the pins dont look like theyve come away from the flex
Sometimes when the health of the battery is poor u also have a problem with the charging circuit of the phone which leads to ur battery health being poor, so 3 possible things the battery has been allowed to deplete to such a level that it no longer has enough juice to start charging, u can buy chargers that the battery plugs into and allow it to charge independently some people just give it a bust with a dc power supply, only for a few seconds and then put it back in the phone and it charges again. 2nd thing it could be a bad battery that goes below its tolerance and wont charge again. 3rd thing u have a faulty charging circuit and the phone never charges properly... tristar ic etc... P.s 4th and 5th lol u could have broken the screen ie damaged the flexes taking it apart again, u could have caused long screw damage etc. Damaged charging flex. My steps on this would be to boost the battery for a second then plug it back into the phone and test its charging correctly using a USB ampmeter