|"..he states the laptop was knocked onto the floor, since then it hasn't charged the battery."|
That's probably the cause of the problem.
Apparently there is no such model as Dell Inspiron 1705.
However, there is a E1705 sub-model in the Inspiron 9400 series.
Use the Service tag "number" to look up the correct model on the Dell site.
Go here for how to find the Service tag "number":
Tell us what it is.
If it IS the E1705 sub-model in the Inspiron 9400 series....
I have only opened up a few laptops. In at least one of them, an Acer Aspire, it had a small board / card that plugs into the mboard that has USB ports and that the power jack is directly connected to (integral, soldered). Some Dell models have that too.
When I looked up info on the web (as I recall I used it's part number to search with, either Acer's on a label on it, or it was printed on the board) , that board has both power related circuits and USB circuits - replacing that board / card MAY fix a problem related to whether the battery is not charging properly, or the battery is not switching properly to be used when you disconnect the AC adapter, or the USB ports there not working If replacing the small board / card doesn't fix the problem, you must replace the mboard.
(In the case of that Acer Aspire laptop, it was dropped. The built in display never worked after that. It worked fine with an external monitor for months after that, then the keyboard and all the USB ports stopped working, including one other USB port in the main mboard. I opened it up and tried making everything was plugged in properly to no avail. The corner of the mboard is physically damaged, but otherwise there is nothing wrong that can be physically seen. The other had no money to risk to fix it, so I did not try replacing the small board or the mboard. It still boots and charges the battery fine, it still displays on an external monitor, but you can't enter a password to get it to load Windows with no way for a keyboard to work.)
Dell™ Inspiron™ 9400/E1705
I looked at the Service manual.
It appears your model has no such separate small board / card.
There are two possible mboards - one has an integrated video adapter - the other one has a slot that a video card plugs into.
You could try opening up the case and making sure all connectors are seated properly. REMOVE the battery, unplug the AC adapter BEFORE you do that, or fiddle with the ram.
If that doesn't help, the only solution is to replace the mboard.
Search the web for :Inspiron E1705 motherboard