My two cents: Moist, not soggy, soil. Fewer roots=less water uptake. If you can keep the soil warm (bottom heat) that will help. Gradually increase light. You might even consider a humidity dome for a little while (bottomless water bottle).
Disclaimer: I've lost a few even using the above steps ;-)
I hope he perks up for you. __________________ Cheryl Chicago, Zone 6a (That's what they say, but it still feels like 5) Growing: Hardy Chicago, Black Mission, Brunswick, Kadota, Ischia Green, Desert King, Osborne Prolific (slow but steady), Malta Black, Violette de Bordeaux, Texas Everbearing, Beall, White Adriatic, Nolo Pink Eyed Lady. Rooting: Ronde de Bordeaux, Celeste, Nero 600 m, Violetta Bayernfeing, Marseilles Black VS, Celeste.