Vostro 3300 wont boot

Hi I've got a vostro 3300 that powered itself off during a bios update and now it wont boot.

On power up the media lights flash right to left then back again I can hear the fan for maybe 10 seconds, it cuts all the power and then immediately cycle repeats. Nothing ever shows on the screen.

To try solve this I have tried reseating the mainboard battery.

I have tried making a fat32 drive with the 3300a12 file  by deleting all partitions on a 500gb ext drive and creating a single 16gb fat32 partition. I used these instructions for creating the files - 

https://www.dell.com/community/Laptops-General-Read-Only/Vostro-3300-BIOS-Update-Failed-Recovery-Procedure-Needed/td-p/5103108

Any help would be much appreciated thanks!