"No point on giving up on this device so quickly...it is an iPhone 7 after all. At the very least, bring it to a reputable micro-solderer to see if they can find and fix the issue. Boot-loopers are tough and can have deep problems and aren't always repairable but most micro-soldering repair shops work on a no fix/no fee basis so there's not much risk involved.
Can you plug it into a USB ammeter to see if there is any current flow? Otherwise, many things can cause a boot-looping device. Give us more history by commenting on this answer.
A few things to try first if you haven't already:
Try a hard reset (Home & Power button for 10 secs)Use a genuine Apple Lightning connectorUse a genuine Apple charging brick and let it charge overnightTry to connect it to different computers (mac/pc if possible) with an updated iTunesPut the phone in recovery mode (search DFU Mode). Careful, this can reset your data Use 3uTools for putting it in and out of Recovery ModeUse 3uTools to flash the firmware (you can't downgrade)Check the condition of all the flexes (with magnification)Disconnect the Front Camera Ribbon from the logic board and reboot your phoneDisconnect the screen assembly completely and see if iTunes will recognize the phone.
I’ve had the same issue on my iPhone 7 Plus, id tried everything, taking the camera cable out, updating the phone, changing the screen and none of them work for me. Until I took out the power button cable and placed it in again which seemed to have fixed it. I’m not sure if this is a permanent fix but it help me get all my data back which was what I really wanted in the first place. Hope this helps
