Going by all the above symptoms I would say the integration relay is dying/dead - the box is clipped to the fuse box and has a orangey/brown plug A quick look to the epc shows 82641-05010 Most are sold used with the fuse box, but should unclip eg. https://www.ebay.co.uk/itm/224366052342 The integration relay is the bit with the white writing on it, IMO make an offer of £30-35   do you get the locking back with the 7.5A in place or not ?