Razer Blade 2017 fans not coming on

I have a Razer Blade 2017 with an i7 7700HQ and GTX 1060. When I turned the laptop on today the fans don't come on at all; I first noticed it when a game started running at very low FPS and Intel XTU said that the CPU was thermal throttling. I had previously undervolted the CPU by 100mV, which seemed to work well for bringing temps down.

I've had a look inside and there's nothing blocking the fans. I've taken out their power plugs and put them back in, and I've updated the BIOS. SpeedFan doesn't recognise any fans in my system.

Can anyone help? Is this a hardware issue? Do I need to replace the fans? When gaming the fans do go a bit insane on this model so I can imagine in three years they might have worn out, but they didn't sound like they were struggling at all before they went.

Thanks in advance!