Blistering hot may be the key to your Tyros mishap. The Tyros has a temperature operating threshold and should be kept within those confines to assure correct operation. If the Tyros itself got too hot within the casing it is possible that that could have caused the malfunction. Another possibility is the AC current you were drawing from may have had irregularities (i.e. spikes, dips, etc. in the current). If the power is not 'clean' power i.e. steady regulated AC, then that could be the reason for the glitch.
A good idea especially if you Gig at several different establishments and the buildings are older or run down a bit, is to get a good AC Line Conditioner that will provide you with steady 'clean' power to your Keyboards, etc. at all times. Furman makes great AC Line Conditioners. There are other good ones out there also. Even in the best case scenario with a brand new establishment with all new electrical wiring there still may be spikes and dips in the voltage and or current. If the spike or dip is too high or too low problems could ensue in the operation of your Keyboards, etc.
AC Line Conditioners are just one more safe-guard in your sound system and gear that helps keep you operational at all times, especially in the critical times.
Another way is refuse to work in extreme temperature situations. Like outside in the sun when the temperature is so hot it could fry an egg on asphalt.
Or where it's so cold if you're not careful the Keys on your keyboard may snap right off. Either that or maybe one of your fingers could do the same.
I'm being facetious of course but I hope you get the picture.
Get the Picture?
PS: You may not mind working in the numbing cold or blistering heat but you've got to think about your poor ol' beloved Tyros, right?
Hope this helps.
Best regards,
Mike