Hey, I am making an Atari Flashback 2 Portable with the cartridge mod. I hooked up with the audio amp, the controls, and the TFT lcd screen, and everything works except for the Lipo rechargeable battery. The FB2 works fine with the regular power plug, but it doesn’t with the LiPo battery which I used was 3.7V 2000mAh, the usb charger port, and the buck converter I have trimmed down to 9V. What am I doing wrong? I need to have the rechargeable battery working on my project. I 3D printed the case I made, so this is the best I can make.