Phone not swtching on only vibrating

This sounds very much like a failed LCD or backlight. Which one it is isn't important since the fix is the same either way; you'll most likely have to replace the screen. The procedure is pretty standard for an Android phone; remove the glued on back panel, then unscrew the midframe bracket. Unplug the battery and remove it, then peel off the display connector. Turn the phone over and separate the display from the midframe, clean the old adhesive and glue on a new LCD. This YouTube video steps you through the whole process.

Infinix HOT 30 LCD Replacement - YouTube

Note that most screen suppliers will take a return if the screen hasn't been installed, so it's important to test the replacement screen first thing to verify that it fixes the problem. Once you remove the back and the rear bracket, you can unplug the original screen and plug the replacement in its stead. Power the phone on and make sure it works, both the display and the touch screen. Assuming everything is good, disconnect the new display and proceed with the repair. If for some reason it doesn't work, you can always just unplug the new screen and return it for a refund.