4.3" 12V TFT LCD RCA Display to 5V

Question

I'm building a portable Raspberry Pi (3B+) handheld and I'm using a 4.3" Car Monitor as a screen. The box says it runs on 12V(+/-10%). I've tested it for a bit and It even runs on as low as 6volts.. I've read multiple threads on forums about 5V hacks for these kinds of displays but have never found any for this kind of PCB..

I've tried many points on the board and tried supplying 5V to those points but haven't found anything to work. I've tried The VCC3.3 point on the top right, 10V capacitor, The small 6pin voltage regulator (i think..) under the 35V capacitor, and tried PIN2, PIN5, PIN6, And tried supplying 5V to all these points and nothing works.. The thing is... I can't find any datasheets for the parts on this board(probably coz this is a chinese board). The only one place I can find info about this board is, https://www.electroschematics.com/tft-car-monitor/ this person pretty much describes each part if that helps, i don't understand most of it coz I'm a total noob in electronics.

Eventually, i want to power this display directly from the USB port on the Pi and power the Pi from a battery pack.

I can test and check how the voltage differs in various points on the board, if that helps figuring this out. Any Help is hugely appreciated.

The PCB: https://i.stack.imgur.com/MdiPC.jpg

Answer 1

Or maybe try it differently ... give 12 V from the power supply, use a croissant. Use one plug for the display and the other connect to the Steep-down converter (very small device and cheap) which reduces the current to e.g. 5 V (i.e. as much as you need for the RB).

Then you will have one power supply with two different voltages for two different devices.