Best way to revive old mycelium?

I have a jar of grain spawn that is about 5 months old, its been sitting in storage at room temperature.

Obviously not ideal, but its a strain that I would like to revive.

I was thinking of just doing a grain-to-grain transfer, and see how it goes.

Or have others had better experience reviving old mycelium in other mediums first? (e.g. to agar, or to liquid first, to revive it?).

If no contaminants i’d go for gtg

My preferred medium for reviving / reinvigorating old mycelium is agar. This has two major advantages: 1) you’ll quickly see if it’s contaminated, without having to commit to a full grain run; 2) you can challenge / stimulate the mycelium by introducing it to different media (for example, run it on a malt-extract-agar plate and then transfer it to a potato-dextrose-agar plate before reintroducing to grain or liquid culture).

You could also do both: agar and G2G. Transfer a single grain kernel to agar at the same time as your G2G (do this for multiple plates, just in case). Then, if the G2G fails, you should at least have something to work with on agar.