opened failed apprentice

Your point being?

Corpses don't have the Failed Apprentice virtue, of course. So it doesn't actually answer the question at all.

you seem to be trying to get a failed apprentice who still has the Gift which goes against the common wisdom and RAW. I would say to go to your troupe and see if they will buy it.

Indeed. If the character is has Failed Apprentice flaw, then he no longer has the Gift (or at least not enough of it) and cannot be opened to Hermetic Magic.

Which is not to say that a character could not be designed as an abandoned apprentice, so that he could complete his apprenticeship under a new master. He simply wouldn't have the Failed Apprentice flaw, but rather a different mix of virtues and flaws depending on how far along his apprenticeship was.

hmmm... abandoned apprentice is a story flaw, so in theory it could be a companion character...

Absolutely.
And it probably should be - it's a character important enough to drive it's own story, and it has (potentially anyway) the Gift.
Fits perfectly fora Gifted Companion, neh

I am not aware of any Virtue or Flaw Abandoned Apprentice in the books. The life and options of one are described in Apprentices p.58f.

A troupe deliberating, whether and/or how to admit a player character who is Gifted and an abandoned apprentice, should consider the following:
(1) A character with her Gift opened for the Hermetic Arts has all the development potential of a full magus character, and with a little time could become as powerful as the other player magi.
(2) An abandoned apprentice can relatively easy become a full magus character: she just needs to find a new master to take her as pupil and thus allow her to finish the apprenticeship, swear the Oath of Hermes and learn the Parma Magica. The player character magi are obvious candidates to become this new master.
(3) This should lead the troupe to look up HMRE p.11 Magi, Companions and Grogs, when determining the 'slot' an abandoned apprentice fills among the characters of its player.

Abandoned apprentices in any case make excellent opponents, as several published adventures show: they know Hermetic Magic and the Order from the inside, and the authors can easily find motivations for them.
Running a campaign around a rogue covenant - like GotF p.114 Fenistal - with all main player characters being abandoned apprentices could also be a lot of fun.

Cheers

Page 12 of Apprentices.

I see. Thanks.