What a frightening proposition: Thunderbolt display where the only working element was the Thunderbolt cable connecting to the MacBook Pro. Yikes!
I’ve been away from my Thunderbolt display for five months and only spent the past day attached. However, in that time, I’ve learned that my Ethernet, USBs, microphone, speakers and camera weren’t working – at all.
I did a search on ‘thunderbolt display reset’ and got this article.
I did the procedure described (unplug everthing from the display and then unplug the power for 30 seconds), but only the USB elements: USB, mic, speakers, camera; worked. The display Ethernet port did not work… so,
I did a MacBook Pro non-volatile RAM reset. This often referred to as PRAM, however PRAM was a feature of the PowerPC systems and haven’t been in production Macs since 2006. This is the popular Command-Option P R key combination, held down shortly after a power cycle, for two chimes (aka POST – Power On Self Test). Still no display.
So, then I did an SMC reset (SMC = System Management Controller) which on a powered off MacBook Pro, with power connected, is the key combination of Command – Option – Shift and the power key. All keys are held down until the power light flickers. Then you know it has been reset.
AND…. it worked like a champ.