Inspiron 15 5567 Crashing / Unstable after BIOS 1.2.8 and driver updates

3 year old Inspiron 15 5567 with after market 1TB SSD drive, running Windows 10.

Had an issue yesterday where sound wouldn't play out of headphones, possibly the first time I've tried connecting headphones. Found a recommended solution on the web to update audio driver. I did this via online Dell Support Assist. This seemed to correct the headphone issue. At the same time Support Assist recommended updating 4 or 5 other drivers, including WiFi, Rapid Storage Technology, Thermal Framework, Management Engine and others I can't remember; also the BIOS to 1.2.8 (From 1.2.3 (?)) .

Anyway, since doing that, my laptop has randomly hung once, and also turned itself off. The second time I thought it was bricked, as it wouldn't respond to pressing the power button. After being left for around 5 minutes the laptop powered up. I've never had an issue like this before, and I suspect the driver & BIOS updates are to blame; it's too coincidental. Has anyone else had this issue, and what can I do to resolve it? The machine is fully update according to Dell Support Assist and Windows update.

Regards.