I have many Nikon D4 bodies and have had the flashing LED problem on at least two of them. The problem has been coming and going. I recently got the problem to go away by taking the Nikon 80-400mm Lens off then put it back on. That particular lens has a known VR problem. The lens works fine if I switch the VR off. I will be tracking that lens carefully now.
Assuming there is nothing with either the lens or the camera body, then yes, your AF-S lens is fully compatible (including autofocus) with the Nikon D3100.
See the 2nd row of the Nikon lens compatibility chart.
If the camera says your lens is not attached, then one of the following is probably happening:
The lens isn't fully rotated and latched into ...
A roll of 35mm 36 exposure film has a tail attached to supply spool with tape. The other end is a leader called a tongue. While the exact length is a changeable, via manufacturers, the average length is 64 ½ inches = 1638-milimeters. The tale and tongue measure about 10 inches = 254-millimeters. Thus, the length suitable for imagining is 1638 – 254 = 1384-...
I don't think there is a specific max weight for the lens mount, as such, I've never really seen that on any camera I've owned (modern or film) as typically heavy lenses should be supported directly and not via the camera body.
While the M50 mount is welded to the inner metal frame, this not is heavy duty. I would not recommend supporting a heavy lens with ...
My guess is that some electrical connection inside the lens looses contact in some mechanical situations, maybe getting stretched when going beyond 200mm focal length.
The over-exposure might come from such a faulty internal connection: the iris not closing, thus taking the photo full-open at f/5.6 although commanded to do f/11. This would result in a two-...
This was going to be a comment.
As the lens is extended, the "lever arm" gets longer. Maybe the rear lens flange is a bit loose and is creating a gap at the longer focal length leading to improper electrical connection.
I would recommend close inspection of the lens to camera connection as the lens is extended as a first step.
Throw the MicroSD card. Or use it for something not important as MicroSD, not with adapter. Adapter is other device (passive but intermediate) and can cause some unpleasant side effects. Your camera is for SD cards so buy SD card and use it.
The problem with camera can be caused by battery not keeping the charge (battery with end of charging resource, ...
As you can see, the port you are probably using, is an input port for a wired remote control, not an output port for flash sync.
You may make it work, if you connect one flash onto the hotshoe and set the other flashes on optical triggering if they support that.
I'm making an educated guess that the FC-16 triggers you have are rebranded 2.4 MHz Godox FC-16 triggers, since that's what I see packaged with your speedlight model (which is not a rebranded Godox speedlight) on Amazon.
No speedlight uses a 6.5mm connector. So, I assume a studio strobe/monolight is being used, here. You've probably got the cable plugged ...
The blue light usually indicates file transfer so it may think that it is connected to a computer and trying to transfer files. Try plugging in a USB cable when it is on then pulling it out and see if that gets it out of the loop.
Also try cleaning all the ports and checking if the coin shaped battery needs replacing.