I doubt your yeast is dead. Pasteur preserved wine by "heating it to only about 50–60 °C (122–140 °F) for a brief time to kill the microbes, and that the wine could subsequently be aged without sacrificing the final quality." (https://en.wikipedia.org/wiki/Pasteurization)
The same article reports heating to 161F kills "99.999% of the number of viable micro-organisms in milk. This is considered adequate for destroying almost all yeasts, molds, and common spoilage bacteria and also to ensure adequate destruction of common pathogenic, heat-resistant organisms ..."