I know I shouldn't have bought 3 Salvia greggii Heatwave last Fall, overwintered them heeled into garden and stretched their advertised hardiness for Zone 6.

I've got them and I want your advice on what to do with them. No sense in tossing them if there's a chance to baby them into survival/bloom for this year.

Stalks are all brown except for a few that still have a little green on them. I read conflicting instructions about old versus new growth and pruning.

I know I'm in a wait and see situation but could you tell me what signs of life I should look for?

New leaves on existing brown stems? New stems altogether? Since I've read some people prune after last frost (May 15th here) should I cut any little bit off tops of stems? Assume that's for better shape/height regulation in warmer zones but could also be to stimulate new growth...if there's any left in plants. Maybe cut a tiny bit off couple stems on each plant to see if they're still white in there?

Plants don't come out of soil like roots are dead as I've experienced with a couple goners of other plants so far so I'm assuming there may still be some life there.

Don't know and need your experience here in spite of my own stupidity/inexperience.

Plants are about 1 foot tall if that helps. Heatwave series is dwarf.

Thanks in advance for your best advice as to what to look for in terms of signs of life and/or whether I should do anything other than just "wait and see" and for how long.

I wouldn't do anything. (Hard to do, I'll attest to that!) Maybe wait a month or so, I'd bet on you seeing some growth by then.
My coccinea got zapped by frost and displayed the same characteristics as you describe. They're coming back strong and blooming again.
It's hard to wait and see, and I'm the most impatient person around. But sometimes that's all ya got!

I sowed S. coccinea 'Lady in Red' and 'Coral Nymph" under lights and they germinated well. 'Lady' is getting first set of true leaves. I love them for their attractiveness to Hummingbirds. They were easy to care for and flowered through relatively mild November here last year.

I won't be tossing the Heatwave plants anytime soon...I'll baby them for months and see what happens.

If I see any green and the plants don't lift right out of the soil from dead roots I seem incapable of yanking a plant.

They're already drought tolerant, hardy etc, so I can't see what will make this series so great.
But it was pretty! Big flowers, full bushy plant.

Tutti Frutti

If it was started from seed, it is F2 or beyond and can't be Tutti Frutti by definition.