Would you jump directly from A02 to A17?
I jumped one T5500 from A6 to A17 a few weeks back with no issues. It had the old case that has non-removable HDD0 bay. I was getting an error with my X5687s and 24gb DDR-10600R ECC ram that dimm 2 was bad. I ran the update and boom ram came back just fine.
I would run A16 or A17 for all hardware support. Like Retro said though - if you are running VMs, the A17 BIOS came out in April to patch Specter v2, otherwise A16 is the same as far as hardware support.
I personally dont like flashing bios that work because you dont know what you will end up with but A02 is super old and there have been a lot of fixes/support added since then.
*******
As a side note a pair of X5687s will go a long way towards improving your system performance. I just benched my T7500 (which the T5500 can be setup quite equally) - and it benched in the 79th percentile for both the system and GPU tests with a 1070ti...The processors alone came in at the top 91st percentile!
System Score:
https://www.passmark.com/baselines/V9/display.php?id=109957263786
3DMark Score:
https://www.3dmark.com/3dm/29867477
Not too shabby, I'll run a test on my T5500 with 2x x5687s, 24gb a gtx 1060 card for comparison and post later.
**** EDIT TO ADD ****
I dug up the the passmark score from that T5500 I was working on last week with the 1060 card
https://www.passmark.com/baselines/V8/display.php?id=109520808175
Processors actually scored higher : 11833 (T7500) vs 12511 (T5500)
The only major differences are in the GPU (1060 vs 1070ti) and disks (I've spent a lot of time optimizing the T7500 as it s my main workstation). For reference the T5500 is running a single Intel SSD5 545s 256gb off the motherboard sata controller. The T7500 disk setup is in my signature. The T5500 could be setup identically though I dont know if there is enough room for all the disks lol. Either way the systems end up about equal when the parts are the same.
I also just notices the 1060 (though 1 less star) scored 1000 points higher than the 1070ti on 3D??? I'll have to upgrade the T5500 to the latest version of 3DMark and run again...really wierd!