You do not have arms, but you do have movable magnets within your armored casing that allows you to move metallic objects.  You also have arm socket compartments  in which you can have functional arms installed.

You have resistance to poison damage and immunity to disease, and you have advantage on saving throws against being paralyzed or poisoned. You don’t need to eat, drink, or breathe.

When you take a long rest, you spend at least 6 hours in an inactive, motionless state, instead of sleeping. In this state, you appear inert, but you remain conscious

You are encased in thin metal or some other durable material. While you aren’t wearing armor, your base Armor Class is 13 + your Dexterity modifier.

You are designed to be a smart bomb quite literally.  As a Bonus Action, you can begin the ignition process.  At the beginning of your next turn, every creature within 5ft of you must make a Dexterity saving throw (DC 8 plus your Constitution modifier and Proficiency Bonus). On a failed save, a creature takes an amount of d4’s equal to your Character Level in Fire Damage.  On a successful save, they take half damage.  You are immediately put at 0 HP and you must roll your first Death Saving Throw.  If you are at 0 HP at the time of explosion, you automatically fail two Death Saving Throws.  You can only use Explode once per Long Rest.  

If your character dies before using the Explode ability, and their body is still intact (not disintegrated or "smashed to pieces"), the Explode ability is activated on its own.  At the beginning of what would be their next turn in the Initiative Order, they explode.

If the mending spell is cast on you, you can spend a Hit Die, roll it, and regain a number of hit points equal to the roll plus your Constitution modifier (minimum of 1 hit point).

In addition, your creator designed you to benefit from several spells that preserve life but that normally don’t affect Constructs: cure wounds, healing word, mass cure wounds, mass healing word, and spare the dying.