Precision M4600 - Not Booting after BIOS Update

I installed BIOS update A16 to my M4600 and after it went to 100%, the system will no longer POST. No dell logo, no ability to get into BIOS. The hard drive light is bright white, and the battery light next to it flashes White once then 4 times amber, then white again plus 4 times amber, and repeats for a few more times before just settling on non-stop flashing amber.

Pulled and swapped the memory and the hard drive, tried it with and without the battery, also pulled the CMOS battery. Again, no video on the screen, no Dell logo, no POST, no fans on, nothing activity wise other than those flashing lights when I turn it on. I'm thinking something went wrong with the BIOS update even it looked like it completed successfully and I've done hundreds of these to various Dell laptops over the years.

Any ideas what I should try next? I can't find that solid white HD, flashing amber Battery diagnostic code anywhere in any documentation or online so I don't even know where to begin.

Plus it's not under warranty anymore which angers me because it appears the only reason my laptop has been bricked is because I dared install the A16 update that was helpfully published right there on Dell's support page.