I can't find the original post (I'm horrid at navigating the forums) but I'll tag @azygous . They handled that thread & witnessed the chicks untimely demise from the coffee grounds.
Unfortunately we just had a thread on here a few weeks ago of someone who lost chicks due to keeping them on coffee grounds. Caffeine is toxic (and fatal) to almost all animals if they ingest it. It can cause seizures, and ultimately organ failure.