Trouble powering on Devo 7e

I wonder if anyone can help me. I'm having trouble powering on my Devo 7e.
This is a very new transmitter and I installed Deviation a few days ago and all was fine. Yesterday I tried to set up the wiring for adding two future modules. I added Dupont wiring onto the 5 points to allow me to easily plug in and remove the modules. I installed the A7105, with a view to adding the NRF24L01 later. Checked everything a lot and powered on. Nothing works. I think I got lots of ticking sounds. Powered off . Disconnected the A7105 and powered back on. Still nothing.
So not all bad.
When I plug the battery in I get one tick noise. If I then turn on the power switch I get nothing.
If I unplug the battery, turn on the power switch and then replug the battery the transmitter will boot as normal. It even appears to work as normal. It will talk to my Orange RX. Another strange thing. When I turn off the screen dims but the text / picture stays on for 5-10 seconds. I think plugging in the battery gives the transmitter some low amount of power even when off. I think the battery voltage dropped over night.
My original thought was I may have bridged something while soldering, but I really can't see anything and have checked as much as I can using my meter buzz function. The other thought was I've blown a regulator or the like. Other treads talk about how they aren't great. But I can't see anything.
I've seen one other thread with a question similar to this about 2 years ago but it never got an answer I could see (Devo 7 not e).
If anyone has any ideas or has seen this before and fixed it I would appreciate any help.

Can you post a close up photo? This sounds like a weak short,and it's pretty small stuff to work with, so it may be obvious.

Pictures now enclosed.
There's not much to see really as I've removed my mod after the power on trouble started. I've visually inspected my solder points and used my multi meter buzzer to check what could be bridging.
The second picture shows what I was trying to do. I was going to add 4 dual dupont wires for the main connectors and 2 single wires for TMS and TCK. Each module was going to share the dual wires and have either the TMS or TCK. I was going to add the A7105 today and the NRF24L01 later. I didn't get as far as editing the config file to say what modules were installed where.
The third picture show one component I'm unsure about. The small black 3 legged part (don't know it's type) just below where it says THRO-V next to the 2 holes. I'm not sure if that looks healthy? I have seen that burnt out in another picture on this forum. Would it's part type be relevant? Could I have killed it with a power spike?
Again thanks for any help or ideas.

Having trouble adding pics

Going off your description my first guess is you've burnt a transistor who's job it is to turn off the P-FET that switches power on/off. Unlike an N-FET, a P-FET can't turn it's self off, it must be pulled down with a transistor (typically a NPN type BJT) to shut down. Based off your description of how the screen hangs on after power down I believe this to be your issue.

Do you have an LCR meter? Are you capable of SMD soldering? If not you may want to consider paying someone here (John M Barter who does devo mods here and on RCG or someone like that), I'm capable and enjoy working on stuff like that but I just do not have the time to offer you my services... good luck.

Thanks CK.
I don't think my soldering skills are up to working ultra small even if I could work out exactly what part burnt out.
The annoying thing is it was supposed to be a cheap small option to use with DSM to use for my line of sight 250 quad. I didn't need to hardware mod it at all. I thought I would try, one as a cool project and two to have the option of Flysky which I think my Turnigy 9X talks.
I may buy another and just do the software mod. Not sure what to do with the old one. I'm not sure if I could trust it in action.

Bumping my own post to add a related question.
Is the firmware version important when related to what points you bridge?

I was using stock 4.0.1 when I installed my module (i didn't realize it was so old and nightly would be better) and wired the module as above following instructions from.

www.rcgroups.com/forums/showthread.php?t=2570426

Second picture.

I wonder if that caused my power problem. The reason is I've found this image of wiring the same module.

www.rcgroups.com/forums/showthread.php?t...page=56#post27524160

Again second image. The pins that are connected are very different. Is one setup for the old firmware and one for the new? I really don't want to burn out another transmitter.

Wanna sell me the old one?

What country are you in? UK here.

Yes, the witing changed after 4.0.1. Please follow the links entry in the left-hand menu, and then the module installation guide about halfway down that to the official instructions, which are maintained and updated as things change, unlike blog entries, YouTube videos and forum posts.