M4300 Stack Firmware Upgrade

Hi All,

We have been updating our M4300's firmware to latest. We have a range of stacked and unstacked switches and they have been fine.

We have one stack which comprises of 8 physical M4300-52G-PoE+ switches.

Currently they are running 12.0.15.7 and I simply tried to move to next version 12.0.17.6. I start the upload the non-active image using https and it starts the process. After about 5-10 mins the page stops working and the ping drops (everything that connects to these switches goes offline) All lights are amber (that have connected ports). We left this for around 30-40 mins. In the end I had to power down these switches (all 8) and bring them all back on. 

Connections were restored at this point but the images are what they were at before.

Anyone else experienced this or have any suggestions. Is there any logs on these devices to see if I can see whats going on?

Thanks,