Apple TV 2 Jailbreaked with IOS 4.3

Hi all,

After 2 years of no use of ATV2, I want to use now with my NAS Synology with app DS Video.
So I tried to reconnect to my TV but now it’s not working (blinking lights), so I’m trying to decide to restore and update it.
So, what’s the best choice for me now?

Have I to download the last IOS version (6.2.1) and jailbreak in tethered mode or I can jailbreak it with 5.3 and seasonpass?
Is it feasible?

What do you suggest now, i have to upload my certificates for 4.3 so I can go back with this iOS?

Thank you in advance.