sony ericsson k800i won't turn on

Hi! So my dads old sony ericsson phone with lots of old holiday photos wont turn on and we're not sure what to do. Phone doesnt have a memory card they are directly on the phone. When the charger is plugged in a red light at the bottom sometimes stays on for a few minutes or simply flashes for a few seconds then stays off but it ultimately still doesn't turn on. We've bought a new charger and battery and nothing has helped to turn it on so far. Ive read online that the red blinking indicates either a battery problem or about updating/flashing the firmware or a corrupted erom? ive also seen some things about a wotanserver but im not sure what that is. A lot of other forums with this problem are more 10 years old so any helpful links and advice is outdated. Could somebody please help my dad really wants to get these old family photos and videos from the phone and to stop worrying about them. Thank you.