[rev2.0WHS] Not Working - Receiver and Right Hand Transmitter Soldered

[aliasboink]

Hello,

I am rather new to soldering on PCB's and flashing firmware. I have done the following:

• I have soldered the transmitter and the right hand transmitter.
• I have flashed the QMK firmware on Arduino (2 Pro Micro 5V Arduinos, tested with both).
• I have flashed the firmware on the transmitter and the receiver using the docker compose setup.
• Once the transmitter is plugged in, only the Arduino green LED lights up.

Currently no key presses work on the keyboard. I have checked the connections with a multimeter and currently I am at a loss.

Can the firmware flash without the YJ-14015 module being soldered on properly?
How could I proceed with troubleshooting from this point onward?

Edit: I've ditched the initial right hand PCB altogether and soldered a new one. Here is a GitHub repository with pictures of all the components: https://github.com/aliasboink/rev2.0WHS_pictures

[aliasboink]

The columns all have roughly 3V.
The rows all basically ground (pull down resistor I presume?).
Every column goes to 0 upon a keypress, specifically testing with K35 in my case for the most apart.
Any idea what could be the issue?

[StoyanDimitrov]

Do you happen to have stable power source (i.e new batteries)? Lately the YJ-14015 modules are power-hungry.

[aliasboink]

Yep, using new batteries, they measure 3V.