This multimeter is the cheapest you can buy on Aliexpress in 2026. It does all the basic multimeter functions, and it works reasonably well. It also lacks any kind of protection if you use it wrong. It will definitely emit smoke if you connect it across voltage when you have the probes connected to measure current. It also lacks a backlight. 

On the inside there are a couple points on the circuit board that get 9v from the battery when the unit is switched on. That's a good place to hook up a tiny backlight. A small length of a 9-12v cob led strip works for this lcd backlight. You can get a few meters of cob led strips for super cheap on aliexpress or amazon. I found that the kind that separates (or allows you to cut it) every inch or two works great for this.

You cut it right at the solder pads, solder some little jumper wires to it, add a ~330 ohm resistor if you want to dull the brightness a bit (and conserve battery). Note that this is an always-on led if connected to the pins as described. So, when the multimeter is on, the backlight is on too, so it will draw a few mA, and there's no auto-off timer. 

Here are some photos of the operation. A picture of where the wires go. Look for the little + and - in the picture.  And the led strip with wires and resistor connected, and the final glued in-place assembly.

Another option for these little meters is using a rechargeable 9v battery.