I have four of these laptops sitting on a card table. Three of them had an issue where the hard drive light was on, the battery light was blinking, and the wifi light was on. I also tried replacing the CMOS battery twice and it didn't change anything.[br]
Using the E7440 manual (https://www.dell.com/support/manuals/en-us/latitude-e7440-ultrabook/late7440om-v3/device-status-lights?guid=guid-2bd338a4-db1f-492f-a464-d6d4c8643e7a&lang=en-us), it mentions that my light configuration indicates that the memory modules are detected, but had an error. I tried different RAM configurations and found a faulty RAM stick. That fixed the issue on two of the laptops (I haven't tried the others but I am hopeful).
If I am reading your diagnostic codes correctly, 3 amber, 1 white, (https://www.dell.com/support/manuals/en-us/latitude-14-7440-2-in-1-laptop/lati_7440_sm/system-diagnostic-lights?guid=guid-2ec2929d-8ae9-48ff-840f-78aaaa18e148&lang=en-us) then it should have been fixed by the CMOS battery replacement. Since that didn't fix the issue, perhaps there is a problem with the CMOS Battery Connector socket itself. I would try a few different CMOS batteries, before calling it quits. You could buy a used E7440 and swap parts, but as @lucasfrc this laptop is old and not supported anymore.
I wish you well.