In Disk Management mark the 7 partition Active.
Run startup repair from 7 dvd 3 times.
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Rt click the partition and select Mark partition as active.
Startup repair can't fix everything at once. It needs to create bootmgr, the Boot folder, and the bcd store with correct entries. You might get away with fewer runs - 3 to be sure.
I would do it a quicker way - but this is easier for the OP.