AU has deployed 5,000 peace keepers. That is great.
As usual, you have your own odd interpretation of the facts. All that has happened is that its "Peace and Security Council" has "agreed, in principle" to send troops there. That is a long way from having troops there, for three reasons:
(1) The AU does not have troops to send; they must be found from willing countries.
(2) After the troops are found, it will require the agreement of agreement of Burundi or the approval of at least 2/3 of African presidents (or similar). The first is out: the Burundians are opposed to it and have made cheeky remarks about how they are the ones who send out peacekeepers (Somalia).
(3) Once (1) and (2) are done, it will probably be time to hit the "donors" for something. The AU does have a "Peace Fund", but African countries have not seen their way clear to putting any real money into it.