Electrical – Lights won’t go out with 4-way and 3-way switches in any position

Switching worked until today. Removed power to circuit. Removed 4-way switch and tested for continuity, SAT. Jumpered wires on 4-way to make
3-way circuit. Turned power on and no change, lights won't turn off. Turned power off and removed all switches. Continuity SAT on 3-way switches. Installed all new switches and problem still there. The lights are fluorescent. How can ballast lights fail and override switches and stay on? This doesn't make any since to me. I have a electronic background and my electrical is very good also. This doesn't add up where the load overrides the switching source. Have you seen this type of failure before. I am very puzzled by the new switches not fixing the problem? Please help. How do I test the lights. I can remove one at a time from the circuit to determine which one is causing the problem. I thought I understood electrical wiring until now?

Update:

Thanks for your input. I live near Augusta Ga. I recently bought this home and didn't discover this issue until now. The house was built in 2004. I decided to make a logic table with switch positions to understand the issue at hand.

Basicly I found with 3-way #1 in UP, 4-way UP and 3-way #2 Down lights "OFF". Changed 3-way #1 to down position and lights "ON". Next I turned 3-way #2 UP and lights stayed "ON". First failure. Next I placed 4-way down and lights stayed "ON". Then I placed 3-way #1 up and lights went "OFF".

I will now remove all switches and verify all wiring (travelers, hot, neutral etc.). Check continuity and look for grounds. All switches are in same room about 10 feet apart from each other. The load consists of 5 sets of lights. I will make a sketch of how everything is wired together and compare it to standard wiring designs published for 3-way/4-way switching. Again thanks for everyone's input.