Book Identification - Children's SF

I am trying to remember the title of a children's SF book I once read, maybe 20 to 25 odd years ago.

I don't have a great number of details (and some of what I recall may be completely wrong), but the details (such as they are):

1) A war between two alien groups ended, and some technology that should have been destroyed was instead imprinted into a human baby. A few years later, both groups find this out and attempt to retrieve it.

2) The main characters are the child, and an alien that I believe was called "Yacob" (or similar) who was sent to protect the child / retrieve the technology, and the antagonists were the other group of aliens that had previously lost the war and were trying to get the technology to start it up again (again; I don't remember the exact details, but I think it was a fairly simple black & white good vs bad scenario, being a children's book and all).

3) There was a scene in which Yacob/the alien gives the child blue food, who complains that it's blue, and the alien states "close your eyes and it's just food".

4) The alien had a space shuttle / some other piece of tech disguised as a van. I vaguely recall a scene in which it is under attack and it flies. Or something.

Again, apologies for the lack of detail.

Thank you in advance!

Tercano