It sounds like the battery in the MV might be dead. I don't have an MV, but I do have its cousin, the ME Super. The battery is used only for the meter and electronically controlled shutter. It is designed so that it can be used in B and at 1/100 second without battery power. Try a new battery.
The ZX-M sounds more serious. I can't help you there. There's a guy named Eric Hendrickson who has an excellent reputation for repairing Pentax cameras. His website is
Home. However, it might be more cost-effective to replace the camera. ZX-M's are readily available on eBay for around $50, which is probably less than the repair cost.
Paul Noble