Likely your iPhone has a short circuit somewhere on the motherboard from being dropped, water spills, or using a bad cheap after-market charger/cable, or software update.
To fix this kind of issue with your dead iPhone you need to take it to a local phone repair shop that specializes in motherboard repair service, data recovery, board level repair micro soldering experts in Vancouver.
If your data is not backed up on iCloud and you really need those memorable pictures or other content, then choose the right repair shop that understands the advanced electronic circuit repair and has a good reputation in fixing water damaged phones with a very high success rate.
Since 2004 Cellfixx is one the most trusted cell phone repair shop that does not only repair phones complicated issues related to the motherboard which requires a highly trained technician with a good understanding of Electronics repair that other competitors simply refuse to fix because of their lack of expertise in understanding Electronics and do simply screen replacement and battery
replacement in Vancouver.