Well, then I was just using my pi 3b+, but suddenly it stopped working, and there was only the red light, but not the green light. I tried many sd cards, but it still didn't work. and I found out that when I touch the Polyfuse of RPI3B+, the red light goes out and then I thought "is it a Polyfuse problem or something?". Well I'm really not that good using raspberry pi or with engineering/programming and there's no way to buy a new RPI because where I live there's none of them or it's just really expensive.
Raspberry pi 3B+ 32gb SanDisk Ultra SD card 5v 3amp Power supply (non-oficial)
i would be very appreciated if someone could help me, real thanks!