Not balanced, far too restrictive
The ability score increase is unusual. No class relies on constitution as its primary ability but it is commonly the most important secondary attribute. I'd say this is on the weaker side as one loses the specialization bonuses granted by other races' ability bonuses.
The speed of 10 feet per turn is abysmal and will result in turns spent waiting to get into range. It shoehorns this race towards a ranged playstyle, but unfortunately even that will be problematic because the character is blind beyond the first 50 feet. Playing this race I would be tempted to pick the Monk class just to eventually get better mobility, but the natural defense feature synergizes poorly with Monk AC.
Truesight is way too powerful as an innate racial ability. The spell True Seeing is the usual way to get it and it is a sixth level spell. See also this question that concerns the power of Truesight: How powerful would an always-on Truesight ability be for a PC?
The energy cannon is poorly defined. What does one roll to attack with it? Does it prevent the character from using their hand, further shoehorning them into very specific playstyles? Is the PC proficient with it? The damage output is swingy and falls behind other options soon after the first level, which wouldn't necessarily be a problem for an extra ranged attack given as a tactical option, but the attack has such abysmal range it's probably not as good as you think. The radiant damage can offer some neat situational advantages, though, as it often deals extra damage or triggers special effects against undead.
Conclusion
This feels like a very classic case of a gimmick race that simply lacks the typical flexibility that allows an interesting variety of gameplay. It has such severe limitations that it is heavily discouraged from taking most classes, forcing the player taking it into the confines of a very particular playstyle. I would discourage enforcing a very particular strategy even for a homebrew class, and emphatetically so for races.
