Hey Antonio, it's possible to do a motherboard replacement of your device. Follow this video (restart to replace), it should give you a good idea and a technique. You can purchase a motherboard from eBay but here are some things to consider:
-Is the seller giving a fair return policy?
-Does the seller have a good reputation?
-Has the seller sold products like this with good reviews?
-Does the product have good reviews?
-Are you purchasing the correct motherboard and are you sure that the details of your phone match with the details of seller?
Something like this would be a wise decision. Be careful when shopping.
-The dis-assembly video I showed you works for the model you have.
-For some reason, if you are unable to find the certain motherboard for your device, I was able to find this and this. The tips stated above can be applied to this website as well. This website seems to state that there is a six month warranty and one of the sellers stated that is the product is defective within the first three months, they will replace it.
-Let me know how it goes.