Latitude 5400 system diagnostic light codes https://www.dell.com/support/manuals/en-us/latitude-14-5400-laptop/latitude_5400_servicemanual/system-diagnostic-lights?guid=guid-ae612708-ca76-4e00-b219-a848947f5283&lang=en-us Latitude 5400 chromebook diagnostic LEDs  https://www.dell.com/support/manuals/en-us/latitude-14-5400-chrome-laptop/lati5400chrome_sm/diagnostic-leds?guid=guid-e0aef7bd-f282-4302-94d6-792e4aaa21ed&lang=en-us

@davehaughton "4 white lights & 2 amber lights" should actually be a 2 amber lights and 4 white lights which indicates a Memory/RAM failure. Since you now have no sign of life try this. · Start off with the easy things. Disconnect the power from the computer by unplugging the power cord from your computer. Disconnect all external devices from the computer. Remove the battery (if you can) Now hold the power button depressed for about 30 sec-1min. Reapply the AC power adapter and see if your computer does show any sign of life. · Next you want to check your power supply. Make sure it has the proper voltages. Check to make sure that connectors are not bend etc. Check the DC-in jack of your laptop. Make sure there is no corrosion, debris etc. that prevents it from working. Clean it of any debris etc, use a few puffs of air to clean it out. If none of this works, get a ammeter and see if your laptop draws any amperage from the charger. After that, you need to check and see if your motherboard even gets power. For that of course, you need to open it up. Post Some good pictures of what you see. That way we can see what you see. Adding images to an existing question · Based on the original error code, it is also possible that this is a bad RAM module or a bad LCD. So remove the RAM, clean the contacts with a pencil eraser. Do it gentle so as to not destroy the module. Replace it and restart. If you have more than one module, remove it and just leave one connected. · Use the · Dell Latitude 5400 service manual to work on your computer.

Memory or Read-Only Memory (ROM) failure If competent, take the memory out and try the following - if there are two DIMMS then try each one in each slot to see if there is any change, if just one DIMM the try both slots and also try no RAM installed and it should produce a 2,3 code. Manual at https://dl.dell.com/content/manual36483742-dell-g15-5515-service-manual.pdf?language=en-us and memory at P. 24 Remember to insert and remove at 45 degree angle. Good luck Got warranty?

Hello,

2,8 normally means there is an LCD failure. Have you experienced anything of that sort with your machine? Have you run the hardware diagnostics on the machine recently? This is a video on how to run the diags https://dell.to/2RuW1w7 ^SA

Hi, pattern 2 amber, 4 white is for Memory or RAM failure.  First thing i would try is reseating RAM. Second thing i would do is flea power release: Flea power is the residual static electricity that remains on the computer even after it has been powered off and the battery has been removed. The following procedure provides the instructions on how to conduct flea power release: Turn off your computer. Remove the base cover. Press and hold the power button for 15 seconds to drain the flea power. Replace the base cover. Turn on your computer. Dell forgot to add up one step for this ( its to unplug battery doing flee power release) Third thing i would do is hold power button for 30 seconds ( more on link bellow): https://www.dell.com/support/article/si/en/sibsdt1/sln304892/how-to-reset-real-time-clock-rtc-to-recover-your-dell-portable-system?lang=en Also try this if your product is supported: http://dell.to/2u4vSud The HDD and DATA should be unharmed as it doesnt have anything to do with above troubles. Regards,