Patio uplights and underground connection boxes

I'm in the process of replacing the uplights in our patio that have never worked since we moved in and this is not a surprise considering that water has entered the light fitting in most of them. I'm estimating these to have been in place for 10 years or so.

The underground junction boxes are Wiska 308 boxes. When I opened one of these, there was a bit of water at the bottom of the box and the connector screws were rusty, so it seems they have lost their waterproof properties over time.

I would like some advise as to what is the best way to create a new waterproof connection, given that I cannot entirely replace the box (perhaps just the lid).

Also, is there an easier connector type so that I don't have to fiddle with tiny screws in such a confined space.

Thanks.

Wiska 308 boxes are not designed to be buried, unless they are filled with so-called magic gel.
https://www.tlc-direct.co.uk/Products/WKONEGEL.html

Better to site junction boxes above ground or use boxes designed for burying, Like these
https://www.tlc-direct.co.uk/Products/PRUBX03.html

resin filled joint another option.

Easiest option is to put the lid back on your wiska box, drill a hole in the lid, and then fill with magic gel.

https://www.tlc-direct.co.uk/tcl/search?query=Magic+gel&Submit=Search

It might be a good idea to replace those screwed connections with something like a wago connector before you fill the box.