Meta unfortunately got a bad name with their alarms mainly because of bad fitting and owners allowing the internal battery to die, which once their bike battery died would shut down the alarm locking it. I've had 4 of them a 351A and 3 357s, 2 wired in by a mate and 2 by me, I didn't have any problems whatsoever, unlike Data units
Mata alarms are good, which is why Yamaha UK had them as their official system for a why, back when you couldn't get bike insurance on some models without having an alarm fitted. From my experience fitting and removing them it's not straightforward, hence all the problems, all the wires are black and labeled, with the labels being removed after fitting. There are six possible types M355, M351A, M357(T), M357TV2, M357TV2-1 & Defcom(3 or T). Yours is most likely one of the 357 versions but it could be a 351 old stock fitted by a stealer, these system (as all where back the day) had to be fitted by registered fitters to get the insurance cert. That said many where fake photo copies.
Look on the bottom of the alarm unit there will be a sticker that will identify your version.
The units can be wired almost countless ways, there is default but many weren't wired to it and a lot didn't even get all wired in, stealers taking shortcuts i.e. time it takes around 4-5 hrs to wire one in properly. The fact all the wires are black and designed to be hard wired means it's a almost complete strip down of the bikes bodywork, tank, etc to get at the loom and then you've got to pretty much strip the loom. This made hot wiring on the street impossible even in a garage extremely difficult and very time consuming, that's their strength, scumbags avoided them.
Wired in as it was intended you've got little chance of getting one out without doing all the above mentioned, the one's I wired in for sure you won't. This is also their Achilles heel stealers cut corners as mentioned and just run wires along the loom without over tapping or cutting in, so it's a just a matter of tracing things. This was one of the main reasons insurance companies dropped them and the fact manufactures started to hard wire their own systems into the the bikes.
If you've just gone and cut things the system will have locked itself. Unless it's obvious which wire you've cut goes with which in order to rejoin them, you're going to have to strip as mentioned above and then you're going to need either the reset key or code depending on what model you've got. One saving grace is most owners never change the factory set code same on many other types. If you can't do that yourself and it's been wired in properly, it's going to be very costly, if you can find someone willing to touch it. Fingers crossed you've got a crap stealer fitment and you can sort it.
Basically you've got really only one choice remove the whole thing and then hope you can replace the bikes wiring back together.
Good luck mate.