Need help getting my 29gal going again

[PaphMadMan]

LED output can decrease with use, but would not have changed during the time it was unused.

How long have the orchids been in the new tank? It would take a few months for low light to cause any visible problems other than lack of growth. Is there any natural light at all?

Do you have any way measuring temperature and humidity? If not, that's a high priority both for long term health of plants and determining what the problem may be. Do you have a fan for internal air movement? How open is the tank to outside air? Tightly covering the tank would hold humidity but a fan for circulation would be a necessity.