Make sure that all parts came in good shape and no apparent damage is done on the way. Flash Tamagotchi software to Wemos D1 board just to make sure it works.

Start by soldering push buttons. Make sure not to apply to much tin, as it will complicate battery holder installation in the future.

Please remove sticking part of the pins

Solder headers to the Wemos D1 module. Long part of the header should be directed to the motherboard. Make sure to align them right, use motherboard as an aligning tool. When soldered it will be tightly pressed against battery socket.

Start with just one pin each side and double check your work. Then you can proceed to other pins.

Solder headers to the motherboard from the back side. Do not use too much solder, just enough to make solid connection. Excessive solder will block battery connector later on

Assemble 4 brass rings on the screen. Use 4  M2 screws.

Use remaining 4 M2 screws to connect screen to the motherboard firmly. Make sure the screen is well aligned.

For battery connector to fit properly it is necessary to cut screen pins short. Pin length should be barely above brass PCB surface.

Double check screen alignment and solder screen in place. Do not leave large tin bulges.