I have an XL1 that was recently serviced. The camera powers up and works perfectly in VCR mode but when switched to any of the record functions nothing shows up in the viewfinder and the power light shuts off after a few seconds. Pressing the standby button brings the power light back on and the viewfinder flickers, but again after a few seconds it shuts off again. Any thoughts? The iris/shutter control was replaced and the camera was working fine before this.

You should take it back to the service provider.

It was serviced by a technician and myself at the tv station we work at. We can't figure out the problem.

Factory-authorized service is your only option now. The XL1 is too old to be serviced directly by Canon, but you can contact Canon USA for a list of authorized third-party repair facilities by calling 1-800-OK-CANON.