Looks like our flash triggers arrived at much the same time, Makar0n. And yeah... I ran into the same issues as you.
There's also another problem you may potentially hit - you need a top-notch fibre optic cable in order to trigger the strobes (at least for Sea&Sea YS-D1 strobes). I believe it has to be a 613-core cable in order to transit enough light from the trigger's LEDs. My old cables worked with the GH2 camera flash, but were not good enough for the trigger.
Like you, I took the trigger apart. I found the solution was to fit the circuit board in sideways. Here's how:
1) Replace the wires to the hotshoe and LED board with longer ones, so you've got more room to work. (I also replaced the LEDs with more powerful ones, but that still wasn't enough to make up for shitty fibre cables.)
2) Carve out a block of polystyrene to fit the space in the housing. Slice in half so you've got a top and bottom to sandwich the LEDs between. The thickness of the top slice is important to ensure the LEDs sit at the right height to meet the fibre optic cables. Carve little notches in the polystyrene for the LEDs and LED board. Fit back together into one block.
3) Wrap it all up with duct tape so it looks professional (well, kinda... ) and doesn't shed polystyrene bits everywhere. The main circuit board tucks neatly underneath.
4) Insulate the bottom battery with a small rubber band or bike inner tube (a road bike tyre works well) so the sides can't touch the battery contact - you only want the top battery to touch.
5) I used the little plastic cap from my battery packaging to hold the two batteries in a stack with the metal contact running up the side.
6) Use a larger rubber band or inner tube (I recommend a mountain bike) to go around everything and hold it all in place.
It may take a couple of attempts to get the right dimensions of polystyrene block, but once you've found it, it should just wedge itself in place and sit firmly with no tape or glue required.
I got this working just before I went to the Solomons for a week. It works like a dream - I love it. With the fast strobe recycle times, I was able to get shots that would have been impossible previously.