This is commonly known as touch ic disease caused by a fractured pad on M1. The repair you will need is to have the touch ic recalled or replaced along with a trace repair to M1 pad. You can get this repair completed with a micro soldering tech. https://www.aonemobiles.com.au/2017/01/t...-ic-no-touch-on-your-iphone/
Hi Jessica, It sounds like you have a tristar issue which is commonly caused by charging the device with no genuine or MFI certified chargers. Tristar is replaceable although you will need seek a Technician that can do Micro Soldering and Motherboard repairs . https://www.aonemobiles.com.au/2017/05/n...-power-phone/
To be on the safe side it would be recommended to change the battey it's hard to say with out seeing it. It's most likely just scraped the top and is fine for now, but if you drop your phone again and its sparked it could trigger of a burn.
EDIT. I saw this post as as a 6+ not a 6s+ below comment is incorrect for this model. In the 6s+ I would suggest to replace the screen as the touch ic is mounted to the screen flex. 6+ has a common issue called touch ic disease, this in fact is a board level issue. The touch ic is fractured on the line called m1 the reason it works on reboot is that the board is heating up and allowing connection for a split time then cooling down and then losing touch again. You will need to get this repaired via micro solderer. https://www.aonemobiles.com.au/2017/01/t...-ic-no-touch-on-your-iphone/
Restarting can be caused by some small parts also like you cameras proximity flex charging dock, I would disconnect these and see if that helps. Other causes could be the swi filter causing re boot every 2 minutes this is normall caused by pry damage. Tristar failure can also be a cause. If you decide to replace the board you could still face the same problem if the above suggestions has not been rulled out.
There could be a couple of things that can cause this. You could have a faulty battey/ gas gauge that will do it. It could also have firmware corruption. Or even a tristar ic that will cause your phone to do this, mainly if bad chargers are used car or home. Try get your device into dfu or recovery and update with iTunes. You may get a error if so post hear for next step.
Considering that this started after a battey change I would be inclined to think you possibly have pry damage around the battery connector, there is a swi filter Knoked off that commonly cause this, Or secondly your initial issue may not of been tha battery. You may have a faulty tristar ic that can also cause the symptoms. You will need to get this looked at by a board level tech.