Did my tank cycle or is the biofiliter dead?

I recently read an article where they talked about cycling a 150gal tank in
3-4 days by adding septic tank bacteria powder to speed up the cycle.
FISHLESS cycle of course. Anybody ever tried this?

Never replace a bio-wheel unless it is physically broken.
It sounds like your tank is in the middle of the cycle to me. Do daily
water
changes to keep the poisons down and keep monitoring levels. When ammonia
and nitrite have been zero for more than a day or so, you're cycled.