B737 MAX 8 Captain reported that Maintenance improperly applied an MEL procedure. After diverting to another airport; the High-Pressure Shutoff Valve was found incorrectly locked in the open position by previous Maintenance.

Narrative

We received a MAX in ZZZ1 that arrived from ZZZ. In ZZZ the crew wrote up the #2 Cowl Valve Light was illuminated. Contract Maintenance in ZZZ MEL'd the #2 HPSOV (High-Pressure Shutoff Valve) (36-XX-XXX) per Maintenance Control. The MEL has an M procedure that locks the HPSOV in the closed position. The crew flew to ZZZ1. In ZZZ1; the crew mentioned that they went around a couple times because they had difficulty getting stabilized because the MEL requires 60% N1 in icing conditions. Preflighting; we discussed the MEL and were under the assumption everything was normal. After de-icing and engine start; we turned on the #2 Engine Anti-Ice. The Engine Anti-Ice and Cowl Valve Light was illuminated. We thought per the MEL that was normal and it would extinguish above 60% N1. It did not. We were clear of icing conditions in the climb-out fairly quickly. We discussed whether the lights seemed right. Determined it was worth a SATCOM call to Dispatch. They deferred us to Maintenance Control. They were all baffled. After much deliberation; I asked Maintenance Control if I had engine anti-ice protection. They could not guarantee it. Since icing conditions were expected on arrival; Dispatch had us divert to ZZZ2. ZZZ2 Maintenance discovered ZZZ Contract Maintenance locked the valve in the incorrect open position. However; they were able to fix the problem and clear the MEL. We then continued to ZZZ3.Perform maintenance correctly. Have the MEL specify clearly what lights may be illuminated; if any.