I can’t help with firmware updates, but I can tell you there are TWO different hardware versions of the 960 Drives, and each version has a different firmware!
How I ran into this… I was building a Raid 0 array for data storage, and the 2 Ultra II 960’s I bought were 2 different units, with different firmwares!!!
That prevented me from using them, as I wanted IDENTICAL DRIVES for Raid 0 use…
I bitched and moaned here until Sandisk told me they would do a ONE TIME Swap, and the told me which SSD they wanted me to send back, and they then sent another so I would have two identical hardware and firmware for both Raid 0 SSD’s…
BUT… SanDisk said It was a ONE TIME Exchange!
I asked if they would identify firmware or hardware revision on the Boxes, so I could Pre Determine which to buy in the future…
And They Said: NO.
As Good as Sandisk Ultra II’s have been, I have not bought any more for Raid Use… And because of that they lost out on nearly 20 purchases… since 2017…
