We are dealing with the boot looping isse but not while imaging. Our issue occurs during warm reboots. We have found that the Intel Intergrated Sensor is causing this issue along with addtional issues with USB ports. There is only 1 driver available for this model since it is the newest chipset. There have been issues with the driver on other models also in the past. I would suggest uninstalling the driver and test out how that goes. Intel does need to address this issue though.

forgot to mention that the endless loop in the Dell logo won't happen right after i put the usb, the image has to start and at the last reboot before finishing the image is where the loop starts, all laptops i have are brand new, and when removing and putting back in the usb, finishes the image, my concern is for future issues that might require a re imaging, i can't re image anymore.

still no one has an idea of what could this be? anyone from dell in this forum?

Have you done the BIOS 1.6.1 update that came out about 10 days ago? That was supposed to address a few issues.

i haven't, but apparently i'll have to do that to all my equipment before running an image if that is the case, is there any way to report this badge of equipment to dell? apparently some of my team members are having issues with the 5420 imaging too 

UDATE:

New BIOS 1.6.1 messed up with my audio and display drivers, speakers won't work on laptop and Dell WD19S docking station is not displaying image on monitors connected with type P connection, tested on different docking station in my office, same issue replicates, i recommend not to update the BIOS cause dell doesn't have another version available on his drivers section, so it cannot be downgraded

I will ask if you updated the rest of the drivers as there are updates for display, network and audio?  Here is the link to the last BIOS https://www.dell.com/support/home/en-us/drivers/driversdetails?driverid=t77tj&oscode=wt64a&productcode=latitude-5430-laptop

I'm currently having the same issue with all of ours as well as the 7330's. With the USB in it wont boot into anything be it F12/F2/or a partition on the internal hard drive. it simply gets stuck in a boot loop tell the USB is removed. I searched for hours in the bios setting for anything related to the tpm or intrusion detection features and nothing i did helped. I also set it from Raid to ACHI im on bios version 1.7

Windows 10 might get stuck in a infinite loading Windows cycle. The following workaround may help with this problem:

Hold the FN (Function key) down while powering on the system.
Still holding the FN key, start tapping the Windows key to bypass the issue.
This should bring up the login screen.

How will this work when trying to boot from a USB stick?