Connecting two hardwares to 5v and ground power off the arduino nano

Hello, I'm trying to connect many input to my arduino nano (actually an elegoo v3 https://www.amazon.it/gp/product/B0716S43Q2/ref=ppx_yo_dt_b_asin_title_o01_s02?ie=UTF8&th=1 ) so I soldered to it some headers so that I can plug a set of inputs and the relative ground comfortably. It works well and I everything is fine, I ran some code and it receives every pushbutton.

I also connected to it a rotary switch (every rotation corresponds to a set resistors that lets me recognize the selection based on the analog value) connected through the analog, 5V and ground and everything works.
I then connected separatedly a little OLED screen ( https://www.amazon.it/gp/product/B076BJZ42H/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 ) through the A4 and A5 pins and ground and 5V with some pushbuttons (but not the rotary switch) and it worked fine.

Then the problem bumped up when I tried to connect both the rotary switch and the screen, that caused the arduino to power off immediately.
My first thought was some kind of short-circuit, but the soldering isn't touching anything apart from the right pins, and also everything worked fine before I connected both the screen and the rotary switch. The arduino powers up again as soon as I disconnect one of the two devices. I'm powering the arduino through a USB on my keyboard, but I tried to power it directly from my pc and nothing changed.

What could be causing the problem?

Time to check things with an Ohm Meter (DVM) ;).

Time to master soldering techniques, review what YouTube has to offer.

Thank you, I'll try to check it

I would like to, but I only have a solder pistol with a big round point, it's really hard to make a good solder in a so tiny spot, so for now I have to use it until I'll buy a smaller one