Neville and the Do-Over

The Battle of Hogwarts is over, but Neville can't join in the celebration. The device in his pocket haunts him (weighing on his sorrow). He stole it, in case it came to this. Now he's going to use it, but what happens to his plan, when Hermione goes to check on him? (NL & HG get stuck in 1975, & pass as 5th yrs & twins)[Non-Circular TimeTravel/AU]