Following a four-month investigation, Samsung Electronics Co. Ltd. announced at a press conference on Sunday the cause of the Galaxy Note 7 overheating and explosions that led to a very costly recall.

After looking at possible hardware and software issues and testing 200,000 phones, Samsung, along with three independent industry organizations, came to the conclusion that two different battery designs were at fault, for different reasons.

D.J. Koh, Samsung’s head of mobile, said at the press conference that in order to regain the public’s trust, the company was obligated “to provide you with a cause” for the self-combusting smartphone. The first battery that led to a phone recall was basically too big, according to the investigation, leading to complications that caused the phone to overheat.

Samsung changed its battery supplier after recalling the first batch of phones. It’s reported that Samsung was in somewhat of a rush to get the next batch of phones out, and to some degree this is why a welding defect in the second battery was overlooked. This second default also caused some phones to overheat.

In an effort to further regain the public’s trust, Samsung has released what it’s called an Eight Point Battery Safety Check for batteries in all Samsung devices. It also appointed a battery advisory board consisting of academics. The safety tests include: durability testing, visual inspection, x-ray, charge and discharge testing, testing of total volatile organic compounds, disassembling testing, accelerated usage testing and open circuit voltage testing.

Samsung said that although those tests were protocol in the past, the company has now implemented “new and enhanced” safety measures with the aim of “zeroing in on areas for improvement.” Those measures include testing devices in extreme circumstances, whether it be inclement weather conditions or user misuse, even though neither were related to the recall.

Samsung has a mountain to climb with regard to trust issues, given that “exploding phone” could endure in smartphone history. What’s more,some critics were not pleased with the way Samsung dealt with the crisis, citing a lack of transparency and a too-passive recall.

Consumer trust in the company should become apparent when Samsung releases its new Galaxy S flagship this coming spring. However, its much better-than-expected preliminary fourth-quarter profits appeared to show that, financially at least, the company had shaken off the recall.

Here’s more detail on the battery issues in an infographic from Samsung:

Photo credit: Mike via Flickr